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Lacey SE, Graziadei A, Pigino G. Extensive structural rearrangement of intraflagellar transport trains underpins bidirectional cargo transport. Cell 2024; 187:4621-4636.e18. [PMID: 39067443 PMCID: PMC11349379 DOI: 10.1016/j.cell.2024.06.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Revised: 05/06/2024] [Accepted: 06/28/2024] [Indexed: 07/30/2024]
Abstract
Bidirectional transport in cilia is carried out by polymers of the IFTA and IFTB protein complexes, called anterograde and retrograde intraflagellar transport (IFT) trains. Anterograde trains deliver cargoes from the cell to the cilium tip, then convert into retrograde trains for cargo export. We set out to understand how the IFT complexes can perform these two directly opposing roles before and after conversion. We use cryoelectron tomography and in situ cross-linking mass spectrometry to determine the structure of retrograde IFT trains and compare it with the known structure of anterograde trains. The retrograde train is a 2-fold symmetric polymer organized around a central thread of IFTA complexes. We conclude that anterograde-to-retrograde remodeling involves global rearrangements of the IFTA/B complexes and requires complete disassembly of the anterograde train. Finally, we describe how conformational changes to cargo-binding sites facilitate unidirectional cargo transport in a bidirectional system.
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2
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Bonnefoy S, Alves AA, Bertiaux E, Bastin P. LRRC56 is an IFT cargo required for assembly of the distal dynein docking complex in Trypanosoma brucei. Mol Biol Cell 2024; 35:ar106. [PMID: 38865178 PMCID: PMC11321045 DOI: 10.1091/mbc.e23-11-0425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 05/24/2024] [Accepted: 06/03/2024] [Indexed: 06/13/2024] Open
Abstract
Outer dynein arms (ODAs) are responsible for ciliary beating in eukaryotes. They are assembled in the cytoplasm and shipped by intraflagellar transport (IFT) before attachment to microtubule doublets via the docking complex. The LRRC56 protein has been proposed to contribute to ODAs maturation. Mutations or deletion of the LRRC56 gene lead to reduced ciliary motility in all species investigated so far, but with variable impact on dynein arm presence. Here, we investigated the role of LRRC56 in the protist Trypanosoma brucei, where its absence results in distal loss of ODAs, mostly in growing flagella. We show that LRRC56 is a transient cargo of IFT trains during flagellum construction and surprisingly, is required for efficient attachment of a subset of docking complex proteins present in the distal portion of the organelle. This relation is interdependent since the knockdown of the distal docking complex prevents LRRC56's association with the flagellum. Intriguingly, lrrc56-/- cells display shorter flagella whose maturation is delayed. Inhibition of cell division compensates for the distal ODAs absence thanks to the redistribution of the proximal docking complex, restoring ODAs attachment but not the flagellum length phenotype. This work reveals an unexpected connection between LRRC56 and the docking complex.
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Affiliation(s)
- Serge Bonnefoy
- Trypanosome Cell Biology Unit, Institut Pasteur, Université de Paris Cité, INSERM U1201, Paris, France
| | - Aline Araujo Alves
- Trypanosome Cell Biology Unit, Institut Pasteur, Université de Paris Cité, INSERM U1201, Paris, France
| | - Eloïse Bertiaux
- Trypanosome Cell Biology Unit, Institut Pasteur, Université de Paris Cité, INSERM U1201, Paris, France
- Sorbonne Université, école doctorale complexité du vivant, ED 515, 7, quai Saint-Bernard, case 32, 75252 Paris Cedex 05, France
| | - Philippe Bastin
- Trypanosome Cell Biology Unit, Institut Pasteur, Université de Paris Cité, INSERM U1201, Paris, France
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3
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Ewerling A, May-Simera HL. Evolutionary trajectory for nuclear functions of ciliary transport complex proteins. Microbiol Mol Biol Rev 2024:e0000624. [PMID: 38995044 DOI: 10.1128/mmbr.00006-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2024] Open
Abstract
SUMMARYCilia and the nucleus were two defining features of the last eukaryotic common ancestor. In early eukaryotic evolution, these structures evolved through the diversification of a common membrane-coating ancestor, the protocoatomer. While in cilia, the descendants of this protein complex evolved into parts of the intraflagellar transport complexes and BBSome, the nucleus gained its selectivity by recruiting protocoatomer-like proteins to the nuclear envelope to form the selective nuclear pore complexes. Recent studies show a growing number of proteins shared between the proteomes of the respective organelles, and it is currently unknown how ciliary transport proteins could acquire nuclear functions and vice versa. The nuclear functions of ciliary proteins are still observable today and remain relevant for the understanding of the disease mechanisms behind ciliopathies. In this work, we review the evolutionary history of cilia and nucleus and their respective defining proteins and integrate current knowledge into theories for early eukaryotic evolution. We postulate a scenario where both compartments co-evolved and that fits current models of eukaryotic evolution, explaining how ciliary proteins and nucleoporins acquired their dual functions.
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Affiliation(s)
- Alexander Ewerling
- Faculty of Biology, Institute of Molecular Physiology, Johannes Gutenberg-University, Mainz, Germany
| | - Helen Louise May-Simera
- Faculty of Biology, Institute of Molecular Physiology, Johannes Gutenberg-University, Mainz, Germany
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4
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Marshall WF. Chlamydomonas as a model system to study cilia and flagella using genetics, biochemistry, and microscopy. Front Cell Dev Biol 2024; 12:1412641. [PMID: 38872931 PMCID: PMC11169674 DOI: 10.3389/fcell.2024.1412641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Accepted: 05/13/2024] [Indexed: 06/15/2024] Open
Abstract
The unicellular green alga, Chlamydomonas reinhardtii, has played a central role in discovering much of what is currently known about the composition, assembly, and function of cilia and flagella. Chlamydomonas combines excellent genetics, such as the ability to grow cells as haploids or diploids and to perform tetrad analysis, with an unparalleled ability to detach and isolate flagella in a single step without cell lysis. The combination of genetics and biochemistry that is possible in Chlamydomonas has allowed many of the key components of the cilium to be identified by looking for proteins that are missing in a defined mutant. Few if any other model organisms allow such a seamless combination of genetic and biochemical approaches. Other major advantages of Chlamydomonas compared to other systems include the ability to induce flagella to regenerate in a highly synchronous manner, allowing the kinetics of flagellar growth to be measured, and the ability of Chlamydomonas flagella to adhere to glass coverslips allowing Intraflagellar Transport to be easily imaged inside the flagella of living cells, with quantitative precision and single-molecule resolution. These advantages continue to work in favor of Chlamydomonas as a model system going forward, and are now augmented by extensive genomic resources, a knockout strain collection, and efficient CRISPR gene editing. While Chlamydomonas has obvious limitations for studying ciliary functions related to animal development or organ physiology, when it comes to studying the fundamental biology of cilia and flagella, Chlamydomonas is simply unmatched in terms of speed, efficiency, cost, and the variety of approaches that can be brought to bear on a question.
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Affiliation(s)
- Wallace F. Marshall
- Department Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, United States
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5
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Rao VG, Subramanianbalachandar V, Magaj MM, Redemann S, Kulkarni SS. Mechanisms of cilia regeneration in Xenopus multiciliated epithelium in vivo. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.06.14.544972. [PMID: 37398226 PMCID: PMC10312767 DOI: 10.1101/2023.06.14.544972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Cilia regeneration is a physiological event, and while studied extensively in unicellular organisms, it remains poorly understood in vertebrates. In this study, using Xenopus multiciliated cells (MCCs) as a model, we demonstrate that, unlike unicellular organisms, deciliation removes the transition zone (TZ) and the ciliary axoneme. While MCCs immediately begin the regeneration of the ciliary axoneme, surprisingly, the assembly of TZ is delayed. However, ciliary tip proteins, Sentan and Clamp, localize to regenerating cilia without delay. Using cycloheximide (CHX) to block new protein synthesis, we show that the TZ protein B9d1 is not a component of the cilia precursor pool and requires new transcription/translation, providing insights into the delayed repair of TZ. Moreover, MCCs in CHX treatment assemble fewer (∼ 10 vs. ∼150 in controls) but near wild-type length (ranging between 60 to 90%) cilia by gradually concentrating ciliogenesis proteins like IFTs at a select few basal bodies. Using mathematical modeling, we show that cilia length compared to cilia number influences the force generated by MCCs more. In summary, our results question the requirement of TZ in motile cilia assembly and provide insights into how cells determine organelle size and number.
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6
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Mitra A, Loseva E, Peterman EJG. IFT cargo and motors associate sequentially with IFT trains to enter cilia of C. elegans. Nat Commun 2024; 15:3456. [PMID: 38658528 PMCID: PMC11043347 DOI: 10.1038/s41467-024-47807-2] [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: 07/22/2023] [Accepted: 04/12/2024] [Indexed: 04/26/2024] Open
Abstract
Intraflagellar transport (IFT) orchestrates entry of proteins into primary cilia. At the ciliary base, assembled IFT trains, driven by kinesin-2 motors, can transport cargo proteins into the cilium, across the crowded transition zone. How trains assemble at the base and how proteins associate with them is far from understood. Here, we use single-molecule imaging in the cilia of C. elegans chemosensory neurons to directly visualize the entry of kinesin-2 motors, kinesin-II and OSM-3, as well as anterograde cargo proteins, IFT dynein and tubulin. Single-particle tracking shows that IFT components associate with trains sequentially, both in time and space. Super-resolution maps of IFT components in wild-type and mutant worms reveal ciliary ultrastructure and show that kinesin-II is essential for axonemal organization. Finally, imaging cilia lacking kinesin-II and/or transition zone function uncovers the interplay of kinesin-II and OSM-3 in driving efficient transport of IFT trains across the transition zone.
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Affiliation(s)
- Aniruddha Mitra
- Department of Physics and Astronomy and LaserLaB, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Elizaveta Loseva
- Department of Physics and Astronomy and LaserLaB, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Erwin J G Peterman
- Department of Physics and Astronomy and LaserLaB, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
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7
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Leung M, Steinman J, Li D, Lor A, Gruesen A, Sadah A, van Kuijk FJ, Montezuma SR, Kondkar AA, Radhakrishnan R, Lobo GP. The Logistical Backbone of Photoreceptor Cell Function: Complementary Mechanisms of Dietary Vitamin A Receptors and Rhodopsin Transporters. Int J Mol Sci 2024; 25:4278. [PMID: 38673863 PMCID: PMC11050646 DOI: 10.3390/ijms25084278] [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: 03/12/2024] [Revised: 04/02/2024] [Accepted: 04/04/2024] [Indexed: 04/28/2024] Open
Abstract
In this review, we outline our current understanding of the mechanisms involved in the absorption, storage, and transport of dietary vitamin A to the eye, and the trafficking of rhodopsin protein to the photoreceptor outer segments, which encompasses the logistical backbone required for photoreceptor cell function. Two key mechanisms of this process are emphasized in this manuscript: ocular and systemic vitamin A membrane transporters, and rhodopsin transporters. Understanding the complementary mechanisms responsible for the generation and proper transport of the retinylidene protein to the photoreceptor outer segment will eventually shed light on the importance of genes encoded by these proteins, and their relationship on normal visual function and in the pathophysiology of retinal degenerative diseases.
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Affiliation(s)
- Matthias Leung
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Jeremy Steinman
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Dorothy Li
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Anjelynt Lor
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Andrew Gruesen
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Ahmed Sadah
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Frederik J. van Kuijk
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Sandra R. Montezuma
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Altaf A. Kondkar
- Department of Ophthalmology, College of Medicine, King Saud University, Riyadh 12271, Saudi Arabia;
| | - Rakesh Radhakrishnan
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
| | - Glenn P. Lobo
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN 55455, USA; (M.L.); (J.S.); (D.L.); (A.L.); (A.G.); (A.S.); (F.J.v.K.); (S.R.M.)
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8
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Patel MB, Griffin PJ, Olson SF, Dai J, Hou Y, Malik T, Das P, Zhang G, Zhao W, Witman GB, Lechtreck KF. Distribution and bulk flow analyses of the intraflagellar transport (IFT) motor kinesin-2 support an "on-demand" model for Chlamydomonas ciliary length control. Cytoskeleton (Hoboken) 2024. [PMID: 38456596 PMCID: PMC11380706 DOI: 10.1002/cm.21851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 02/22/2024] [Accepted: 02/23/2024] [Indexed: 03/09/2024]
Abstract
Most cells tightly control the length of their cilia. The regulation likely involves intraflagellar transport (IFT), a bidirectional motility of multi-subunit particles organized into trains that deliver building blocks into the organelle. In Chlamydomonas, the anterograde IFT motor kinesin-2 consists of the motor subunits FLA8 and FLA10 and the nonmotor subunit KAP. KAP dissociates from IFT at the ciliary tip and diffuses back to the cell body. This observation led to the diffusion-as-a-ruler model of ciliary length control, which postulates that KAP is progressively sequestered into elongating cilia because its return to the cell body will require increasingly more time, limiting motor availability at the ciliary base, train assembly, building block supply, and ciliary growth. Here, we show that Chlamydomonas FLA8 also returns to the cell body by diffusion. However, more than 95% of KAP and FLA8 are present in the cell body and, at a given time, just ~1% of the motor participates in IFT. After repeated photobleaching of both cilia, IFT of fluorescent kinesin subunits continued indicating that kinesin-2 cycles from the large cell-body pool through the cilia and back. Furthermore, growing and full-length cilia contained similar amounts of kinesin-2 subunits and the size of the motor pool at the base changed only slightly with ciliary length. These observations are incompatible with the diffusion-as-a-ruler model, but rather support an "on-demand model," in which the cargo load of the trains is regulated to assemble cilia of the desired length.
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Affiliation(s)
- Mansi B Patel
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Paul J Griffin
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Spencer F Olson
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Jin Dai
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Yuqing Hou
- Department of Radiology, UMass Chan Medical School, Worcester, Massachusetts, USA
| | - Tara Malik
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Poulomi Das
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Gui Zhang
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Winston Zhao
- Department of Radiology, UMass Chan Medical School, Worcester, Massachusetts, USA
| | - George B Witman
- Department of Radiology, UMass Chan Medical School, Worcester, Massachusetts, USA
| | - Karl F Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
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9
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Moran AL, Louzao-Martinez L, Norris DP, Peters DJM, Blacque OE. Transport and barrier mechanisms that regulate ciliary compartmentalization and ciliopathies. Nat Rev Nephrol 2024; 20:83-100. [PMID: 37872350 DOI: 10.1038/s41581-023-00773-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/19/2023] [Indexed: 10/25/2023]
Abstract
Primary cilia act as cell surface antennae, coordinating cellular responses to sensory inputs and signalling molecules that regulate developmental and homeostatic pathways. Cilia are therefore critical to physiological processes, and defects in ciliary components are associated with a large group of inherited pleiotropic disorders - known collectively as ciliopathies - that have a broad spectrum of phenotypes and affect many or most tissues, including the kidney. A central feature of the cilium is its compartmentalized structure, which imparts its unique molecular composition and signalling environment despite its membrane and cytosol being contiguous with those of the cell. Such compartmentalization is achieved via active transport pathways that bring protein cargoes to and from the cilium, as well as gating pathways at the ciliary base that establish diffusion barriers to protein exchange into and out of the organelle. Many ciliopathy-linked proteins, including those involved in kidney development and homeostasis, are components of the compartmentalizing machinery. New insights into the major compartmentalizing pathways at the cilium, namely, ciliary gating, intraflagellar transport, lipidated protein flagellar transport and ciliary extracellular vesicle release pathways, have improved our understanding of the mechanisms that underpin ciliary disease and associated renal disorders.
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Affiliation(s)
- Ailis L Moran
- School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| | - Laura Louzao-Martinez
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Dorien J M Peters
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.
| | - Oliver E Blacque
- School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland.
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10
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Hwang J, Yanagisawa H, Davis KC, Hunter EL, Fox LA, Jimenez AR, Goodwin RE, Gordon SA, Stuart CDE, Bower R, Porter ME, Dutcher SK, Sale WS, Lechtreck KF, Alford LM. Assembly of FAP93 at the proximal axoneme in Chlamydomonas cilia. Cytoskeleton (Hoboken) 2024. [PMID: 38224153 DOI: 10.1002/cm.21818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 11/27/2023] [Accepted: 11/29/2023] [Indexed: 01/16/2024]
Abstract
To identify proteins specific to the proximal ciliary axoneme, we used iTRAQ to compare short (~2 μm) and full-length (~11 μm) axonemes of Chlamydomonas. Known compoents of the proximal axoneme such as minor dynein heavy chains and LF5 kinase as well as the ciliary tip proteins FAP256 (CEP104) and EB1 were enriched in short axonemes whereas proteins present along the length of the axoneme were of similar abundance in both samples. The iTRAQ analysis revealed that FAP93, a protein of unknown function, and protein phosphatase 2A (PP2A) are enriched in the short axonemes. Consistently, immunoblots show enrichment of FAP93 and PP2A in short axonemes and immunofluorescence confirms the localization of FAP93 and enrichment of PP2A at the proximal axoneme. Ciliary regeneration reveals that FAP93 assembles continuously but more slowly than other axonemal structures and terminates at 1.03 μm in steady-state axonemes. The length of FAP93 assembly correlates with ciliary length, demonstrating ciliary length-dependent assembly of FAP93. Dikaryon rescue experiments show that FAP93 can assemble independently of IFT transport. In addition, FRAP analysis of GFP-tagged FAP93 demonstrates that FAP93 is stably anchored in axoneme. FAP93 may function as a scaffold for assembly of other specific proteins at the proximal axoneme.
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Affiliation(s)
- Juyeon Hwang
- Department of Cell Biology, Emory University, Atlanta, Georgia, USA
| | | | - Keira C Davis
- Department of Cell Biology, Emory University, Atlanta, Georgia, USA
- College of Arts & Sciences, Clayton State University, Morrow, Georgia, USA
| | - Emily L Hunter
- Department of Cell Biology, Emory University, Atlanta, Georgia, USA
- Science Communication Group, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Laura A Fox
- Department of Cell Biology, Emory University, Atlanta, Georgia, USA
| | - Ariana R Jimenez
- Division of Natural Sciences, Oglethorpe University, Atlanta, Georgia, USA
| | - Reagan E Goodwin
- Division of Natural Sciences, Oglethorpe University, Atlanta, Georgia, USA
| | - Sarah A Gordon
- Division of Natural Sciences, Oglethorpe University, Atlanta, Georgia, USA
| | | | - Raqual Bower
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota, USA
| | - Mary E Porter
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota, USA
| | - Susan K Dutcher
- Department of Genetics, Washington University St. Louis, St. Louis, Missouri, USA
| | - Winfield S Sale
- Department of Cell Biology, Emory University, Atlanta, Georgia, USA
| | - Karl F Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Lea M Alford
- Division of Natural Sciences, Oglethorpe University, Atlanta, Georgia, USA
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11
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Lyu Q, Li Q, Zhou J, Zhao H. Formation and function of multiciliated cells. J Cell Biol 2024; 223:e202307150. [PMID: 38032388 PMCID: PMC10689204 DOI: 10.1083/jcb.202307150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 10/29/2023] [Accepted: 11/14/2023] [Indexed: 12/01/2023] Open
Abstract
In vertebrates, multiciliated cells (MCCs) are terminally differentiated cells that line the airway tracts, brain ventricles, and reproductive ducts. Each MCC contains dozens to hundreds of motile cilia that beat in a synchronized manner to drive fluid flow across epithelia, the dysfunction of which is associated with a group of human diseases referred to as motile ciliopathies, such as primary cilia dyskinesia. Given the dynamic and complex process of multiciliogenesis, the biological events essential for forming multiple motile cilia are comparatively unelucidated. Thanks to advancements in genetic tools, omics technologies, and structural biology, significant progress has been achieved in the past decade in understanding the molecular mechanism underlying the regulation of multiple motile cilia formation. In this review, we discuss recent studies with ex vivo culture MCC and animal models, summarize current knowledge of multiciliogenesis, and particularly highlight recent advances and their implications.
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Affiliation(s)
- Qian Lyu
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan, China
| | - Qingchao Li
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan, China
| | - Jun Zhou
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan, China
- State Key Laboratory of Medicinal Chemical Biology, Haihe Laboratory of Cell Ecosystem, College of Life Sciences, Nankai University, Tianjin, China
| | - Huijie Zhao
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan, China
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12
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Dougherty LL, Avasthi P. Determinants of cytoplasmic microtubule depolymerization during ciliogenesis in Chlamydomonas. Life Sci Alliance 2024; 7:e202302287. [PMID: 37813489 PMCID: PMC10561824 DOI: 10.26508/lsa.202302287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 09/29/2023] [Accepted: 10/03/2023] [Indexed: 10/12/2023] Open
Abstract
At the core of cilia are microtubules which establish length and assist ciliary assembly and disassembly; however, microtubules outside of the cilium can regulate ciliogenesis. The microtubule cytoskeleton polymerizes and depolymerizes rapidly. These processes have been studied across various organisms with chemical and genetic perturbations. However, these have generated conflicting data in terms of the role of cytoplasmic microtubules (CytoMTs) and free tubulin dynamics during ciliogenesis. Here, we look at the relationship between ciliogenesis and CytoMT dynamics in Chlamydomonas reinhardtii using chemical and mechanical perturbations. We find that not only can stabilized CytoMTs allow for normal ciliary assembly, but high calcium concentrations and low pH-induced deciliation cause CytoMTs to depolymerize separately from ciliary shedding. In addition, ciliary shedding through mechanical shearing allows cilia to regenerate earlier despite intact CytoMTs. Our data suggest that CytoMTs are not a sink for a limiting pool of cytoplasmic tubulin in Chlamydomonas, depolymerization after deciliation is a consequence rather than a requirement for ciliogenesis, and intact tubulin in the cytoplasm and proximal cilium support more efficient ciliary assembly.
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Affiliation(s)
- Larissa L Dougherty
- Biochemistry and Cell Biology Department, Geisel School of Medicine at Dartmouth College, Hanover, NH, USA
| | - Prachee Avasthi
- Biochemistry and Cell Biology Department, Geisel School of Medicine at Dartmouth College, Hanover, NH, USA
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13
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Gupta M, Pazour GJ. Intraflagellar transport: A critical player in photoreceptor development and the pathogenesis of retinal degenerative diseases. Cytoskeleton (Hoboken) 2023:10.1002/cm.21823. [PMID: 38140908 PMCID: PMC11193844 DOI: 10.1002/cm.21823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Revised: 12/01/2023] [Accepted: 12/08/2023] [Indexed: 12/24/2023]
Abstract
In vertebrate vision, photons are detected by highly specialized sensory cilia called outer segments. Photoreceptor outer segments form by remodeling the membrane of a primary cilium into a stack of flattened disks. Intraflagellar transport (IFT) is critical to the formation of most types of eukaryotic cilia including the outer segments. This review covers the state of knowledge of the role of IFT in the formation and maintenance of outer segments and the human diseases that result from mutations in genes encoding the IFT complex and associated motors.
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Affiliation(s)
- Mohona Gupta
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Suite 213 Biotech II, 373 Plantation Street, Worcester MA USA 01605
- Morningside Graduate School of Biological Sciences, University of Massachusetts Chan Medical School, 55 Lake Avenue North, Worcester MA USA 01655
| | - Gregory J. Pazour
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Suite 213 Biotech II, 373 Plantation Street, Worcester MA USA 01605
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14
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Syu JJ, Chang CH, Chang PY, Liu CH, Yu CJ, Jou TS. Lipid raft interacting galectin 8 regulates primary ciliogenesis. FASEB J 2023; 37:e23300. [PMID: 37997673 DOI: 10.1096/fj.202301943r] [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: 09/23/2023] [Revised: 10/23/2023] [Accepted: 10/26/2023] [Indexed: 11/25/2023]
Abstract
Primary cilium is a specialized sensory organelle that transmits environmental information into cells. Its length is tightly controlled by various mechanisms such as the frequency or the cargo size of the intraflagellar transport trains which deliver the building materials such as tubulin subunits essential for the growing cilia. Here, we show the sialoglycan interacting galectin 8 regulates the process of primary ciliogenesis. As the epithelia become polarized, there are more galectin 8 being apically secreted and these extracellular galectin 8 molecules apparently bind to a lipid raft enriched domain at the base of the primary cilia through interacting with lipid raft components, such as GD3 ganglioside and scaffold protein caveolin 1. Furthermore, the binding of galectin 8 at this critical region triggers rapid growth of primary cilia by perturbing the barrier function of the transition zone (TZ). Our study also demonstrates the functionality of this barrier depends on intact organization of lipid rafts at the cilia as genetically knockout of Cav1 and pharmacologically inhibition of lipid raft both phenocopy the effect of apical addition of recombinant galectin 8; that is, rapid elongation of primary cilia and redistribution of cilia proteins from TZ to the growing axoneme. Indeed, as cilia elongated, endogenous galectin 8, caveolin 1, and TZ component, TMEM231, also transited from the TZ to the growing axoneme. We also noted that the interaction between caveolin 1 and TMEM231 could be perturbed by exogenous galectin 8. Taken together, we proposed that galectin 8 promoted primary cilia elongation through impeding the barrier function of the TZ by interfering with the interaction between caveolin 1 and TMEM231.
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Affiliation(s)
- Jhan-Jhang Syu
- Graduate Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chieh-Hsiang Chang
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Pei-Yu Chang
- Graduate Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chia-Hsiung Liu
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
- Department of Surgery, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chia-Jung Yu
- Department of Cell and Molecular Biology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Department of Thoracic Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Tzuu-Shuh Jou
- Graduate Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
- Center of Precision Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
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15
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Wesselman HM, Arceri L, Nguyen TK, Lara CM, Wingert RA. Genetic mechanisms of multiciliated cell development: from fate choice to differentiation in zebrafish and other models. FEBS J 2023. [PMID: 37997009 DOI: 10.1111/febs.17012] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Revised: 10/17/2023] [Accepted: 11/21/2023] [Indexed: 11/25/2023]
Abstract
Multiciliated cells (MCCS) form bundles of cilia and their activities are essential for the proper development and physiology of many organ systems. Not surprisingly, defects in MCCs have profound consequences and are associated with numerous disease states. Here, we discuss the current understanding of MCC formation, with a special focus on the genetic and molecular mechanisms of MCC fate choice and differentiation. Furthermore, we cast a spotlight on the use of zebrafish to study MCC ontogeny and several recent advances made in understanding MCCs using this vertebrate model to delineate mechanisms of MCC emergence in the developing kidney.
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Affiliation(s)
| | - Liana Arceri
- Department of Biological Sciences, University of Notre Dame, IN, USA
| | - Thanh Khoa Nguyen
- Department of Biological Sciences, University of Notre Dame, IN, USA
| | - Caroline M Lara
- Department of Biological Sciences, University of Notre Dame, IN, USA
| | - Rebecca A Wingert
- Department of Biological Sciences, University of Notre Dame, IN, USA
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16
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Kubo T, Tani Y, Yanagisawa HA, Kikkawa M, Oda T. α- and β-tubulin C-terminal tails with distinct modifications are crucial for ciliary motility and assembly. J Cell Sci 2023; 136:jcs261070. [PMID: 37519241 DOI: 10.1242/jcs.261070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 07/24/2023] [Indexed: 08/01/2023] Open
Abstract
α- and β-tubulin have an unstructured glutamate-rich region at their C-terminal tails (CTTs). The function of this region in cilia and flagella is still unclear, except that glutamates in CTTs act as the sites for post-translational modifications that affect ciliary motility. The unicellular alga Chlamydomonas possesses only two α-tubulin and two β-tubulin genes, each pair encoding an identical protein. This simple gene organization might enable a complete replacement of the wild-type tubulin with its mutated version. Here, using CRISPR/Cas9, we generated mutant strains expressing tubulins with modified CTTs. We found that the mutant strain in which four glutamate residues in the α-tubulin CTT had been replaced by alanine almost completely lacked polyglutamylated tubulin and displayed paralyzed cilia. In contrast, the mutant strain lacking the glutamate-rich region of the β-tubulin CTT assembled short cilia without the central apparatus. This phenotype is similar to mutant strains harboring a mutation in a subunit of katanin, the function of which has been shown to depend on the β-tubulin CTT. Therefore, our study reveals distinct and important roles of α- and β-tubulin CTTs in the formation and function of cilia.
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Affiliation(s)
- Tomohiro Kubo
- Department of Anatomy and Structural Biology, Graduate School of Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan
| | - Yuma Tani
- Department of Cell Biology and Anatomy, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033, Japan
| | - Haru-Aki Yanagisawa
- Department of Cell Biology and Anatomy, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033, Japan
| | - Masahide Kikkawa
- Department of Cell Biology and Anatomy, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033, Japan
| | - Toshiyuki Oda
- Department of Anatomy and Structural Biology, Graduate School of Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan
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17
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Dougherty LL, Avasthi P. Determinants of cytoplasmic microtubule depolymerization during ciliogenesis in Chlamydomonas reinhardtii. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.07.536038. [PMID: 37066348 PMCID: PMC10104144 DOI: 10.1101/2023.04.07.536038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
At the core of cilia are microtubules which are important for establishing length and assisting ciliary assembly and disassembly; however, another role for microtubule regulation on ciliogenesis lies outside of the cilium. The microtubule cytoskeleton is a highly dynamic structure which polymerizes and depolymerizes rapidly to assist in cellular processes. These processes have been studied across various organisms with chemical as well as genetic perturbations. However, these have generated conflicting data in terms of the role of cytoplasmic microtubules (CytoMTs) and free tubulin dynamics during ciliogenesis. Here we look at the relationship between ciliogenesis and cytoplasmic microtubule dynamics in Chlamydomonas reinhardtii using chemical and mechanical perturbations. We find that not only can stabilized CytoMTs allow for normal ciliary assembly, but high calcium concentrations and low pH-induced deciliation cause CytoMTs to depolymerize separately from ciliary shedding. In addition, we find that ciliary shedding through mechanical shearing, cilia regenerate earlier despite intact CytoMTs. Our data suggests that cytoplasmic microtubules are not a sink for a limiting pool of cytoplasmic tubulin in Chlamydomonas, depolymerization that occurs following deciliation is a consequence rather than a requirement for ciliogenesis, and intact CytoMTs in the cytoplasm and the proximal cilium support more efficient ciliary assembly.
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Affiliation(s)
- Larissa L Dougherty
- Biochemistry and Cell Biology Department, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire
| | - Prachee Avasthi
- Biochemistry and Cell Biology Department, Geisel School of Medicine at Dartmouth College, Hanover, New Hampshire
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18
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Mill P, Christensen ST, Pedersen LB. Primary cilia as dynamic and diverse signalling hubs in development and disease. Nat Rev Genet 2023; 24:421-441. [PMID: 37072495 PMCID: PMC7615029 DOI: 10.1038/s41576-023-00587-9] [Citation(s) in RCA: 67] [Impact Index Per Article: 67.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/16/2023] [Indexed: 04/20/2023]
Abstract
Primary cilia, antenna-like sensory organelles protruding from the surface of most vertebrate cell types, are essential for regulating signalling pathways during development and adult homeostasis. Mutations in genes affecting cilia cause an overlapping spectrum of >30 human diseases and syndromes, the ciliopathies. Given the immense structural and functional diversity of the mammalian cilia repertoire, there is a growing disconnect between patient genotype and associated phenotypes, with variable severity and expressivity characteristic of the ciliopathies as a group. Recent technological developments are rapidly advancing our understanding of the complex mechanisms that control biogenesis and function of primary cilia across a range of cell types and are starting to tackle this diversity. Here, we examine the structural and functional diversity of primary cilia, their dynamic regulation in different cellular and developmental contexts and their disruption in disease.
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Affiliation(s)
- Pleasantine Mill
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, Scotland
| | | | - Lotte B Pedersen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark.
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19
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Lee C, Ma Y, Tu F, Wallingford JB. Ordered deployment of distinct ciliary beating machines in growing axonemes of vertebrate multiciliated cells. Differentiation 2023; 131:49-58. [PMID: 37120964 PMCID: PMC10523804 DOI: 10.1016/j.diff.2023.03.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 02/14/2023] [Accepted: 03/11/2023] [Indexed: 05/02/2023]
Abstract
The beating of motile cilia requires the coordinated action of diverse machineries that include not only the axonemal dynein arms, but also the central apparatus, the radial spokes, and the microtubule inner proteins. These machines exhibit complex radial and proximodistal patterns in mature axonemes, but little is known about the interplay between them during motile ciliogenesis. Here, we describe and quantify the relative rates of axonemal deployment for these diverse cilia beating machineries during the final stages of differentiation of Xenopus epidermal multiciliated cells.
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Affiliation(s)
- Chanjae Lee
- Dept. of Molecular Biosciences, University of Texas at Austin, USA
| | - Yun Ma
- Dept. of Molecular Biosciences, University of Texas at Austin, USA
| | - Fan Tu
- Dept. of Molecular Biosciences, University of Texas at Austin, USA
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20
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Arora S, Rana M, Sachdev A, D’Souza JS. Appearing and disappearing acts of cilia. J Biosci 2023. [DOI: 10.1007/s12038-023-00326-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
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21
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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: 5] [Impact Index Per Article: 5.0] [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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22
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Saravanan S, Trischler D, Bower R, Porter M, Lechtreck K. In vivo imaging reveals independent intraflagellar transport of the nexin-dynein regulatory complex subunits DRC2 and DRC4. Mol Biol Cell 2023; 34:br2. [PMID: 36598807 PMCID: PMC9930527 DOI: 10.1091/mbc.e22-11-0524] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/19/2022] [Accepted: 12/23/2022] [Indexed: 01/05/2023] Open
Abstract
Many axonemal proteins enter cilia and flagella on intraflagellar transport (IFT) trains, which move bidirectionally along the axonemal microtubules. Certain axonemal substructures including the radial spokes and outer dynein arms are preassembled in the cell body and transported as multisubunit complexes into flagella by IFT. Here, we used in vivo imaging to analyze the transport and assembly of DRC2 and DRC4, two core subunits of the nexin-dynein regulatory complex (N-DRC). Tagged DRC2 moved by IFT in mutants lacking DRC4 and vice versa, showing that they do not depend on each other for IFT. Simultaneous imaging of tagged DRC2 and DRC4, expressed from transgenes that rescue a corresponding double mutant, mostly showed transport on separate IFT trains, but occasional cotransports were also observed. The results demonstrate that DRC2 and DRC4 are transported largely independently of each other into flagella. These studies suggest that the N-DRC assembles onto the axoneme by the stepwise addition of subunits.
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Affiliation(s)
- Sahana Saravanan
- Department of Cellular Biology, University of Georgia, Athens, GA 30602
| | - Douglas Trischler
- Department of Genetics, Cell Biology, and Development, University of Minnesota Medical School, Minneapolis, MN 55455
| | - Raqual Bower
- Department of Genetics, Cell Biology, and Development, University of Minnesota Medical School, Minneapolis, MN 55455
| | - Mary Porter
- Department of Genetics, Cell Biology, and Development, University of Minnesota Medical School, Minneapolis, MN 55455
| | - Karl Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, GA 30602
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23
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Marshall WF. The flagellar length control system: exploring the physical biology of organelle size. Phys Biol 2023; 20:10.1088/1478-3975/acb18d. [PMID: 36623317 PMCID: PMC9877179 DOI: 10.1088/1478-3975/acb18d] [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: 10/27/2022] [Accepted: 01/09/2023] [Indexed: 01/11/2023]
Abstract
How cells build and maintain dynamic structures of defined size is currently an important unsolved problem in quantitative cell biology. The flagella of the unicellular green algaChlamydomonasprovide a highly tractable model system to investigate this general question, but while the powerful genetics of this organism have revealed numerous genes required for proper flagellar length, in most cases we do not understand their mechanistic role in length control. Flagellar length can be viewed as the steady state solution of a dynamical system involving assembly and disassembly of axonemal microtubules, with assembly depending on an active transport process known as intraflagellar transport (IFT). The inherent length dependence of IFT gives rise to a family of simple models for length regulation that can account for many previously described phenomena such as the ability of flagella to maintain equal lengths. But these models requires that the cell has a way to measure flagellar length in order to adjust IFT rates accordingly. Several models for length sensing have been modeled theoretically and evaluated experimentally, allowing them to be ruled out. Current data support a model in which the diffusive return of the kinesin motor driving IFT provides a length dependence that ultimately is the basis for length regulation. By combining models of length sensing with a more detailed representation of cargo transport and availability, it is now becoming possible to formulate concrete hypotheses to explain length altering mutants.
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Affiliation(s)
- Wallace F Marshall
- Department Biochemistry & Biophysics, University of California San Francisco, San Francisco, CA, United States of America
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24
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Zhao H, Khan Z, Westlake CJ. Ciliogenesis membrane dynamics and organization. Semin Cell Dev Biol 2023; 133:20-31. [PMID: 35351373 PMCID: PMC9510604 DOI: 10.1016/j.semcdb.2022.03.021] [Citation(s) in RCA: 30] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 03/17/2022] [Accepted: 03/18/2022] [Indexed: 12/28/2022]
Abstract
Ciliogenesis is a complex multistep process used to describe assembly of cilia and flagella. These organelles play essential roles in motility and signaling on the surface of cells. Cilia are built at the distal ends of centrioles through the formation of an axoneme that is surrounded by the ciliary membrane. As is the case in the biogenesis of other cellular organelles, regulators of membrane trafficking play essential roles in ciliogenesis, albeit with a unique feature that membranes are organized around microtubule-based structures. Membrane association with the distal end of the centriole is a critical initiating step for ciliogenesis. Studies of this process in different cell types suggests that a singular mechanism may not be utilized to initiate cilium assembly. In this review, we focus on recent insights into cilium biogenesis and the roles membrane trafficking regulators play in described ciliogenesis mechanisms with relevance to human disease.
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Affiliation(s)
- Huijie Zhao
- Center for Cancer Research, NCI Frederick, Laboratory of Cellular and Developmental, Signaling, Frederick, MD 21702, USA
| | - Ziam Khan
- Center for Cancer Research, NCI Frederick, Laboratory of Cellular and Developmental, Signaling, Frederick, MD 21702, USA
| | - Christopher J Westlake
- Center for Cancer Research, NCI Frederick, Laboratory of Cellular and Developmental, Signaling, Frederick, MD 21702, USA.
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25
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Ishikawa H, Moore J, Diener DR, Delling M, Marshall WF. Testing the ion-current model for flagellar length sensing and IFT regulation. eLife 2023; 12:e82901. [PMID: 36637158 PMCID: PMC9891718 DOI: 10.7554/elife.82901] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 01/12/2023] [Indexed: 01/14/2023] Open
Abstract
Eukaryotic cilia and flagella are microtubule-based organelles whose relatively simple shape makes them ideal for investigating the fundamental question of organelle size regulation. Most of the flagellar materials are transported from the cell body via an active transport process called intraflagellar transport (IFT). The rate of IFT entry into flagella, known as IFT injection, has been shown to negatively correlate with flagellar length. However, it remains unknown how the cell measures the length of its flagella and controls IFT injection. One of the most-discussed theoretical models for length sensing to control IFT is the ion-current model, which posits that there is a uniform distribution of Ca2+ channels along the flagellum and that the Ca2+ current from the flagellum into the cell body increases linearly with flagellar length. In this model, the cell uses the Ca2+ current to negatively regulate IFT injection. The recent discovery that IFT entry into flagella is regulated by the phosphorylation of kinesin through a calcium-dependent protein kinase has provided further impetus for the ion-current model. To test this model, we measured and manipulated the levels of Ca2+ inside of Chlamydomonas flagella and quantified IFT injection. Although the concentration of Ca2+ inside of flagella was weakly correlated with the length of flagella, we found that IFT injection was reduced in calcium-deficient flagella, rather than increased as the model predicted, and that variation in IFT injection was uncorrelated with the occurrence of flagellar Ca2+ spikes. Thus, Ca2+ does not appear to function as a negative regulator of IFT injection, hence it cannot form the basis of a stable length control system.
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Affiliation(s)
- Hiroaki Ishikawa
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Jeremy Moore
- Kenyon College, Gambier, and Summer Research Training Program at University of California San FranciscoSan FranciscoUnited States
| | - Dennis R Diener
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany
| | - Markus Delling
- Department of Physiology, University of California, San FranciscoSan FranciscoUnited States
| | - Wallace F Marshall
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
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26
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Kanie T, Ng R, Abbott KL, Pongs O, Jackson PK. Myristoylated Neuronal Calcium Sensor-1 captures the ciliary vesicle at distal appendages. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.06.523037. [PMID: 36712037 PMCID: PMC9881967 DOI: 10.1101/2023.01.06.523037] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The primary cilium is a microtubule-based organelle that cycles through assembly and disassembly. In many cell types, formation of the cilium is initiated by recruitment of ciliary vesicles to the distal appendage of the mother centriole. However, the distal appendage mechanism that directly captures ciliary vesicles is yet to be identified. In an accompanying paper, we show that the distal appendage protein, CEP89, is important for thef ciliary vesicle recruitment, but not for other steps of cilium formation (Tomoharu Kanie, Love, Fisher, Gustavsson, & Jackson, 2023). The lack of a membrane binding motif in CEP89 suggests that it may indirectly recruit ciliary vesicles via another binding partner. Here, we identify Neuronal Calcium Sensor-1 (NCS1) as a stoichiometric interactor of CEP89. NCS1 localizes to the position between CEP89 and a ciliary vesicle marker, RAB34, at the distal appendage. This localization was completely abolished in CEP89 knockouts, suggesting that CEP89 recruits NCS1 to the distal appendage. Similarly to CEP89 knockouts, ciliary vesicle recruitment as well as subsequent cilium formation was perturbed in NCS1 knockout cells. The ability of NCS1 to recruit the ciliary vesicle is dependent on its myristoylation motif and NCS1 knockout cells expressing myristoylation defective mutant failed to rescue the vesicle recruitment defect despite localizing proper localization to the centriole. In sum, our analysis reveals the first known mechanism for how the distal appendage recruits the ciliary vesicles.
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Affiliation(s)
- Tomoharu Kanie
- Baxter Laboratory, Department of Microbiology & Immunology and Department of Pathology, Stanford University, Stanford, CA, 94305
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma, OK, 73112
| | - Roy Ng
- Baxter Laboratory, Department of Microbiology & Immunology and Department of Pathology, Stanford University, Stanford, CA, 94305
| | - Keene L. Abbott
- Baxter Laboratory, Department of Microbiology & Immunology and Department of Pathology, Stanford University, Stanford, CA, 94305
| | - Olaf Pongs
- Institute for Physiology, Center for Integrative Physiology and Molecular Medicine (CIPPM), Saarland University, Homburg, Germany
| | - Peter K. Jackson
- Baxter Laboratory, Department of Microbiology & Immunology and Department of Pathology, Stanford University, Stanford, CA, 94305
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27
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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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28
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Arora S, Rana M, Sachdev A, D'Souza JS. Appearing and disappearing acts of cilia. J Biosci 2023; 48:8. [PMID: 36924208 PMCID: PMC10005925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
The past few decades have seen a rise in research on vertebrate cilia and ciliopathy, with interesting collaborations between basic and clinical scientists. This work includes studies on ciliary architecture, composition, evolution, and organelle generation and its biological role. The human body has cells that harbour any of the following four types of cilia: 9+0 motile, 9+0 immotile, 9+2 motile, and 9+2 immotile. Depending on the type, cilia play an important role in cell/fluid movement, mating, sensory perception, and development. Defects in cilia are associated with a wide range of human diseases afflicting the brain, heart, kidneys, respiratory tract, and reproductive system. These are commonly known as ciliopathies and affect millions of people worldwide. Due to their complex genetic etiology, diagnosis and therapy have remained elusive. Although model organisms like Chlamydomonas reinhardtii have been a useful source for ciliary research, reports of a fascinating and rewarding translation of this research into mammalian systems, especially humans, are seen. The current review peeks into one of the complex features of this organelle, namely its birth, the common denominators across the formation of both 9+0 and 9+2 ciliary types, the molecules involved in ciliogenesis, and the steps that go towards regulating their assembly and disassembly.
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Affiliation(s)
- Shashank Arora
- School of Biological Sciences, UM-DAE Centre for Excellence in Basic Sciences, Kalina Campus, Santacruz (E), Mumbai 400098, India
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29
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Meleppattu S, Zhou H, Dai J, Gui M, Brown A. Mechanism of IFT-A polymerization into trains for ciliary transport. Cell 2022; 185:4986-4998.e12. [PMID: 36563665 PMCID: PMC9794116 DOI: 10.1016/j.cell.2022.11.033] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 11/14/2022] [Accepted: 11/28/2022] [Indexed: 12/24/2022]
Abstract
Intraflagellar transport (IFT) is the highly conserved process by which proteins are transported along ciliary microtubules by a train-like polymeric assembly of IFT-A and IFT-B complexes. IFT-A is sandwiched between IFT-B and the ciliary membrane, consistent with its putative role in transporting transmembrane and membrane-associated cargoes. Here, we have used single-particle analysis electron cryomicroscopy (cryo-EM) to determine structures of native IFT-A complexes. We show that subcomplex rearrangements enable IFT-A to polymerize laterally on anterograde IFT trains, revealing a cooperative assembly mechanism. Surprisingly, we discover that binding of IFT-A to IFT-B shields the preferred lipid-binding interface from the ciliary membrane but orients an interconnected network of β-propeller domains with the capacity to accommodate diverse cargoes toward the ciliary membrane. This work provides a mechanistic basis for understanding IFT-train assembly and cargo interactions.
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Affiliation(s)
- Shimi Meleppattu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Haixia Zhou
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Jin Dai
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Miao Gui
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Alan Brown
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
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30
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Nguyen A, Goetz SC. TTBK2 controls cilium stability by regulating distinct modules of centrosomal proteins. Mol Biol Cell 2022; 34:ar8. [PMID: 36322399 PMCID: PMC9816645 DOI: 10.1091/mbc.e22-08-0373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The serine-threonine kinase tau tubulin kinase 2 (TTBK2) is a key regulator of the assembly of primary cilia, which are vital signaling organelles. TTBK2 is also implicated in the stability of the assembled cilium through mechanisms that remain to be defined. Here we use mouse embryonic fibroblasts derived from Ttbk2fl/fl, UBC-CreERT+ embryos (hereafter Ttbk2cmut) to dissect the role of TTBK2 in cilium stability. This system depletes TTBK2 levels after cilia formation, allowing us to assess the molecular changes to the assembled cilium over time. As a consequence of Ttbk2 deletion, the ciliary axoneme is destabilized and primary cilia are lost within 48-72 h following recombination. Axoneme destabilization involves an increased frequency of cilia breaks and a reduction in axonemal microtubule modifications. Cilia loss was delayed by using inhibitors that affect actin-based trafficking. At the same time, we find that TTBK2 is required to regulate the composition of the centriolar satellites and to maintain the basal body pools of intraflagellar transport proteins. Altogether, our results reveal parallel pathways by which TTBK2 maintains cilium stability.
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Affiliation(s)
- Abraham Nguyen
- Molecular Cancer Biology Program, Duke University School of Medicine, Durham, NC 27710,Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC 27710
| | - Sarah C. Goetz
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC 27710,*Address correspondence to: Sarah C. Goetz ()
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31
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Abstract
The assembly and maintenance of most cilia and eukaryotic flagella depends on intraflagellar transport (IFT), the bidirectional movement of multi-megadalton IFT trains along the axonemal microtubules. These IFT trains function as carriers, moving ciliary proteins between the cell body and the organelle. Whereas tubulin, the principal protein of cilia, binds directly to IFT particle proteins, the transport of other ciliary proteins and complexes requires adapters that link them to the trains. Large axonemal substructures, such as radial spokes, outer dynein arms and inner dynein arms, assemble in the cell body before attaching to IFT trains, using the adapters ARMC2, ODA16 and IDA3, respectively. Ciliary import of several membrane proteins involves the putative adapter tubby-like protein 3 (TULP3), whereas membrane protein export involves the BBSome, an octameric complex that co-migrates with IFT particles. Thus, cells employ a variety of adapters, each of which is substoichiometric to the core IFT machinery, to expand the cargo range of the IFT trains. This Review summarizes the individual and shared features of the known cargo adapters and discusses their possible role in regulating the transport capacity of the IFT pathway.
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Affiliation(s)
- Karl Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
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32
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McCafferty CL, Papoulas O, Jordan MA, Hoogerbrugge G, Nichols C, Pigino G, Taylor DW, Wallingford JB, Marcotte EM. Integrative modeling reveals the molecular architecture of the intraflagellar transport A (IFT-A) complex. eLife 2022; 11:e81977. [PMID: 36346217 PMCID: PMC9674347 DOI: 10.7554/elife.81977] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 11/07/2022] [Indexed: 11/10/2022] Open
Abstract
Intraflagellar transport (IFT) is a conserved process of cargo transport in cilia that is essential for development and homeostasis in organisms ranging from algae to vertebrates. In humans, variants in genes encoding subunits of the cargo-adapting IFT-A and IFT-B protein complexes are a common cause of genetic diseases known as ciliopathies. While recent progress has been made in determining the atomic structure of IFT-B, little is known of the structural biology of IFT-A. Here, we combined chemical cross-linking mass spectrometry and cryo-electron tomography with AlphaFold2-based prediction of both protein structures and interaction interfaces to model the overall architecture of the monomeric six-subunit IFT-A complex, as well as its polymeric assembly within cilia. We define monomer-monomer contacts and membrane-associated regions available for association with transported cargo, and we also use this model to provide insights into the pleiotropic nature of human ciliopathy-associated genetic variants in genes encoding IFT-A subunits. Our work demonstrates the power of integration of experimental and computational strategies both for multi-protein structure determination and for understanding the etiology of human genetic disease.
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Affiliation(s)
- Caitlyn L McCafferty
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of TexasAustinUnited States
| | - Ophelia Papoulas
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of TexasAustinUnited States
| | - Mareike A Jordan
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany
| | - Gabriel Hoogerbrugge
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of TexasAustinUnited States
| | - Candice Nichols
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of TexasAustinUnited States
| | | | - David W Taylor
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of TexasAustinUnited States
| | - John B Wallingford
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of TexasAustinUnited States
| | - Edward M Marcotte
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, University of TexasAustinUnited States
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33
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Finetti F, Onnis A, Baldari CT. IFT20: An Eclectic Regulator of Cellular Processes beyond Intraflagellar Transport. Int J Mol Sci 2022; 23:ijms232012147. [PMID: 36292997 PMCID: PMC9603483 DOI: 10.3390/ijms232012147] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 10/06/2022] [Accepted: 10/10/2022] [Indexed: 11/16/2022] Open
Abstract
Initially discovered as the smallest component of the intraflagellar transport (IFT) system, the IFT20 protein has been found to be implicated in several unconventional mechanisms beyond its essential role in the assembly and maintenance of the primary cilium. IFT20 is now considered a key player not only in ciliogenesis but also in vesicular trafficking of membrane receptors and signaling proteins. Moreover, its ability to associate with a wide array of interacting partners in a cell-type specific manner has expanded the function of IFT20 to the regulation of intracellular degradative and secretory pathways. In this review, we will present an overview of the multifaceted role of IFT20 in both ciliated and non-ciliated cells.
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34
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Mul W, Mitra A, Peterman EJG. Mechanisms of Regulation in Intraflagellar Transport. Cells 2022; 11:2737. [PMID: 36078145 PMCID: PMC9454703 DOI: 10.3390/cells11172737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 08/30/2022] [Accepted: 08/31/2022] [Indexed: 11/30/2022] Open
Abstract
Cilia are eukaryotic organelles essential for movement, signaling or sensing. Primary cilia act as antennae to sense a cell's environment and are involved in a wide range of signaling pathways essential for development. Motile cilia drive cell locomotion or liquid flow around the cell. Proper functioning of both types of cilia requires a highly orchestrated bi-directional transport system, intraflagellar transport (IFT), which is driven by motor proteins, kinesin-2 and IFT dynein. In this review, we explore how IFT is regulated in cilia, focusing from three different perspectives on the issue. First, we reflect on how the motor track, the microtubule-based axoneme, affects IFT. Second, we focus on the motor proteins, considering the role motor action, cooperation and motor-train interaction plays in the regulation of IFT. Third, we discuss the role of kinases in the regulation of the motor proteins. Our goal is to provide mechanistic insights in IFT regulation in cilia and to suggest directions of future research.
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Affiliation(s)
| | | | - Erwin J. G. Peterman
- Department of Physics and Astronomy, and LaserLaB Amsterdam, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
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35
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Jiang X, Shao W, Chai Y, Huang J, Mohamed MAA, Ökten Z, Li W, Zhu Z, Ou G. DYF-5/MAK-dependent phosphorylation promotes ciliary tubulin unloading. Proc Natl Acad Sci U S A 2022; 119:e2207134119. [PMID: 35969738 PMCID: PMC9407615 DOI: 10.1073/pnas.2207134119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 07/23/2022] [Indexed: 12/21/2022] Open
Abstract
Cilia are microtubule-based organelles that power cell motility and regulate sensation and signaling, and abnormal ciliary structure and function cause various ciliopathies. Cilium formation and maintenance requires intraflagellar transport (IFT), during which the kinesin-2 family motor proteins ferry IFT particles carrying axonemal precursors such as tubulins into cilia. Tubulin dimers are loaded to IFT machinery through an interaction between tubulin and the IFT-74/81 module; however, little is known of how tubulins are unloaded when arriving at the ciliary tip. Here, we show that the ciliary kinase DYF-5/MAK phosphorylates multiple sites within the tubulin-binding module of IFT-74, reducing the tubulin-binding affinity of IFT-74/81 approximately sixfold. Ablation or constitutive activation of IFT-74 phosphorylation abnormally elongates or shortens sensory cilia in Caenorhabditis elegans neurons. We propose that DYF-5/MAK-dependent phosphorylation plays a fundamental role in ciliogenesis by regulating tubulin unloading.
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Affiliation(s)
- Xuguang Jiang
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, School of Life Sciences and Ministry of Education Key Laboratory for Protein Science, Tsinghua University, Beijing 100084, China
| | - Wenxin Shao
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, School of Life Sciences and Ministry of Education Key Laboratory for Protein Science, Tsinghua University, Beijing 100084, China
| | - Yongping Chai
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, School of Life Sciences and Ministry of Education Key Laboratory for Protein Science, Tsinghua University, Beijing 100084, China
| | - Jingying Huang
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, School of Life Sciences and Ministry of Education Key Laboratory for Protein Science, Tsinghua University, Beijing 100084, China
| | - Mohamed A. A. Mohamed
- Center for Protein Assemblies, Physics Department, E22, Technical University of Munich, 85748 Garching, Germany
| | - Zeynep Ökten
- Center for Protein Assemblies, Physics Department, E22, Technical University of Munich, 85748 Garching, Germany
| | - Wei Li
- School of Medicine, Tsinghua University, Beijing 100084, China
| | - Zhiwen Zhu
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, School of Life Sciences and Ministry of Education Key Laboratory for Protein Science, Tsinghua University, Beijing 100084, China
| | - Guangshuo Ou
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, School of Life Sciences and Ministry of Education Key Laboratory for Protein Science, Tsinghua University, Beijing 100084, China
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36
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Maurya AK, Sengupta P. The DYF-5 RCK and CDKL-1 CDKL5 kinases contribute differentially to shape distinct sensory neuron cilia morphologies in C. elegans. MICROPUBLICATION BIOLOGY 2022; 2022:10.17912/micropub.biology.000619. [PMID: 35996689 PMCID: PMC9391949 DOI: 10.17912/micropub.biology.000619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 08/03/2022] [Accepted: 08/03/2022] [Indexed: 12/03/2022]
Abstract
The conserved CCRK, RCK, and CDKL5 kinases regulate cilia length in diverse organisms. In C. elegans , DYF-18 CCRK regulates DYF-5 RCK to shape both simple and complex cilia morphologies. The CDKL5 ortholog CDKL-1 has also been suggested to act downstream of DYF-18 but independently of DYF-5 to regulate lengths of simple rod-like cilia. Here we show that CDKL-1 is largely dispensable for regulation of complex cilia structures. Using genetic epistasis experiments, we confirm that CDKL-1 and DYF-5 act independently to control cilia architecture. Our results indicate that multiple kinases act via distinct pathways to regulate unique cilia ultrastructures.
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Affiliation(s)
| | - Piali Sengupta
- Department of Biology, Brandeis University, Waltham, MA, USA
,
Correspondence to: Piali Sengupta (
)
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37
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Conversion of anterograde into retrograde trains is an intrinsic property of intraflagellar transport. Curr Biol 2022; 32:4071-4078.e4. [PMID: 35926510 PMCID: PMC9521741 DOI: 10.1016/j.cub.2022.07.033] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 06/06/2022] [Accepted: 07/14/2022] [Indexed: 12/30/2022]
Abstract
Cilia or eukaryotic flagella are microtubule-based organelles found across the eukaryotic tree of life. Their very high aspect ratio and crowded interior are unfavorable to diffusive transport of most components required for their assembly and maintenance. Instead, a system of intraflagellar transport (IFT) trains moves cargo rapidly up and down the cilium (Figure 1A).1-3 Anterograde IFT, from the cell body to the ciliary tip, is driven by kinesin-II motors, whereas retrograde IFT is powered by cytoplasmic dynein-1b motors.4 Both motors are associated with long chains of IFT protein complexes, known as IFT trains, and their cargoes.5-8 The conversion from anterograde to retrograde motility at the ciliary tip involves (1) the dissociation of kinesin motors from trains,9 (2) a fundamental restructuring of the train from the anterograde to the retrograde architecture,8,10,11 (3) the unloading and reloading of cargo,2 and (4) the activation of the dynein motors.8,12 A prominent hypothesis is that there is dedicated calcium-dependent protein-based machinery at the ciliary tip to mediate these processes.4,13 However, the mechanisms of IFT turnaround have remained elusive. In this study, we use mechanical and chemical methods to block IFT at intermediate positions along the cilia of the green algae Chlamydomonas reinhardtii, in normal and calcium-depleted conditions. We show that IFT turnaround, kinesin dissociation, and dynein-1b activation can consistently be induced at arbitrary distances from the ciliary tip, with no stationary tip machinery being required. Instead, we demonstrate that the anterograde-to-retrograde conversion is a calcium-independent intrinsic ability of IFT.
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38
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Lechtreck KF, Liu Y, Dai J, Alkhofash RA, Butler J, Alford L, Yang P. Chlamydomonas ARMC2/PF27 is an obligate cargo adapter for intraflagellar transport of radial spokes. eLife 2022; 11:74993. [PMID: 34982025 PMCID: PMC8789290 DOI: 10.7554/elife.74993] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 01/03/2022] [Indexed: 12/19/2022] Open
Abstract
Intraflagellar transport (IFT) carries proteins into flagella but how IFT trains interact with the large number of diverse proteins required to assemble flagella remains largely unknown. Here, we show that IFT of radial spokes in Chlamydomonas requires ARMC2/PF27, a conserved armadillo repeat protein associated with male infertility and reduced lung function. Chlamydomonas ARMC2 was highly enriched in growing flagella and tagged ARMC2 and the spoke protein RSP3 co-migrated on anterograde trains. In contrast, a cargo and an adapter of inner and outer dynein arms moved independently of ARMC2, indicating that unrelated cargoes distribute stochastically onto the IFT trains. After concomitant unloading at the flagellar tip, RSP3 attached to the axoneme whereas ARMC2 diffused back to the cell body. In armc2/pf27 mutants, IFT of radial spokes was abolished and the presence of radial spokes was limited to the proximal region of flagella. We conclude that ARMC2 is a cargo adapter required for IFT of radial spokes to ensure their assembly along flagella. ARMC2 belongs to a growing class of cargo-specific adapters that enable flagellar transport of preassembled axonemal substructures by IFT.
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Affiliation(s)
- Karl F Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, United States
| | - Yi Liu
- Department of Biological Sciences, Marquette University, Milwaukee, United States
| | - Jin Dai
- Department of Cellular Biology, University of Georgia, Athens, United States
| | - Rama A Alkhofash
- Department of Cellular Biology, University of Georgia, Athens, United States
| | - Jack Butler
- Department of Cellular Biology, University of Georgia, Athens, United States
| | - Lea Alford
- Division of Natural Sciences,, Oglethorpe University, Atlanta, United States
| | - Pinfen Yang
- Department of Biological Sciences, Marquette University, Milwaukee, United States
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39
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Perlaza K, Mirvis M, Ishikawa H, Marshall W. The short flagella 1 (SHF1) gene in Chlamydomonas encodes a Crescerin TOG-domain protein required for late stages of flagellar growth. Mol Biol Cell 2021; 33:ar12. [PMID: 34818077 PMCID: PMC9236146 DOI: 10.1091/mbc.e21-09-0472] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Length control of flagella represents a simple and tractable system to investigate the dynamics of organelle size. Models for flagellar length control in the model organism, Chlamydomonas reinhardtii have focused on the length-dependence of the intraflagellar transport (IFT) system which manages the delivery and removal of axonemal subunits at the tip of the flagella. One of these cargoes, tubulin, is the major axonemal subunit, and its frequency of arrival at the tip plays a central role in size control models. However, the mechanisms determining tubulin dynamics at the tip are still poorly understood. We discovered a loss-of-function mutation that leads to shortened flagella, and found that this was an allele of a previously described gene, SHF1, whose molecular identity had not previously been determined. We found that SHF1 encodes a Chlamydomonas ortholog of Crescerin, previously identified as a cilia-specific TOG-domain array protein that can bind tubulin via its TOG domains and increase tubulin polymerization rates. In this mutant, flagellar regeneration occurs with the same initial kinetics as wild-type cells, but plateaus at a shorter length. Using a computational model in which the flagellar microtubules are represented by a differential equation for flagellar length combined with a stochastic model for cytoplasmic microtubule dynamics, we found that our experimental results are best described by a model in which Crescerin/SHF1 binds tubulin dimers in the cytoplasm and transports them into the flagellum. We suggest that this TOG-domain protein is necessary to efficiently and preemptively increase intra-flagella tubulin levels to offset decreasing IFT cargo at the tip as flagellar assembly progresses.
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Affiliation(s)
- Karina Perlaza
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94143
| | - Mary Mirvis
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94143
| | - Hiroaki Ishikawa
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94143
| | - Wallace Marshall
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94143
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40
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Yue Y, Engelke MF, Blasius TL, Verhey KJ. Hedgehog-induced ciliary trafficking of kinesin-4 motor KIF7 requires intraflagellar transport but not KIF7's microtubule binding. Mol Biol Cell 2021; 33:br1. [PMID: 34705483 PMCID: PMC8886809 DOI: 10.1091/mbc.e21-04-0215] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The kinesin-4 motor KIF7 is a conserved regulator of the Hedgehog signaling pathway. In vertebrates, Hedgehog signaling requires the primary cilium, and KIF7 and Gli transcription factors accumulate at the cilium tip in response to Hedgehog activation. Unlike conventional kinesins, KIF7 is an immotile kinesin and its mechanism of ciliary accumulation is unknown. We generated KIF7 variants with altered microtubule binding or motility. We demonstrate that microtubule binding of KIF7 is not required for the increase in KIF7 or Gli localization at the cilium tip in response to Hedgehog signaling. In addition, we show that the immotile behavior of KIF7 is required to prevent ciliary localization of Gli transcription factors in the absence of Hedgehog signaling. Using an engineered kinesin-2 motor that enables acute inhibition of intraflagellar transport, we demonstrate that kinesin-2 KIF3A/KIF3B/KAP mediates the translocation of KIF7 to the cilium tip in response to Hedgehog pathway activation. Together, these results suggest that KIF7’s role at the tip of the cilium is unrelated to its ability to bind to microtubules.
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Affiliation(s)
- Yang Yue
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Martin F Engelke
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - T Lynne Blasius
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Kristen J Verhey
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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41
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Noguchi T, Nakamura K, Satoda Y, Katoh Y, Nakayama K. CCRK/CDK20 regulates ciliary retrograde protein trafficking via interacting with BROMI/TBC1D32. PLoS One 2021; 16:e0258497. [PMID: 34624068 PMCID: PMC8500422 DOI: 10.1371/journal.pone.0258497] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 09/28/2021] [Indexed: 01/02/2023] Open
Abstract
CCRK/CDK20 was reported to interact with BROMI/TBC1D32 and regulate ciliary Hedgehog signaling. In various organisms, mutations in the orthologs of CCRK and those of the kinase ICK/CILK1, which is phosphorylated by CCRK, are known to result in cilia elongation. Furthermore, we recently showed that ICK regulates retrograde ciliary protein trafficking and/or the turnaround event at the ciliary tips, and that its mutations result in the elimination of intraflagellar transport (IFT) proteins that have overaccumulated at the bulged ciliary tips as extracellular vesicles, in addition to cilia elongation. However, how these proteins cooperate to regulate ciliary protein trafficking has remained unclear. We here show that the phenotypes of CCRK-knockout (KO) cells closely resemble those of ICK-KO cells; namely, the overaccumulation of IFT proteins at the bulged ciliary tips, which appear to be eliminated as extracellular vesicles, and the enrichment of GPR161 and Smoothened on the ciliary membrane. The abnormal phenotypes of CCRK-KO cells were rescued by the exogenous expression of wild-type CCRK but not its kinase-dead mutant or a mutant defective in BROMI binding. These results together indicate that CCRK regulates the turnaround process at the ciliary tips in concert with BROMI and probably via activating ICK.
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Affiliation(s)
- Tatsuro Noguchi
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Kentaro Nakamura
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Yuuki Satoda
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Yohei Katoh
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Kazuhisa Nakayama
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan
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42
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Abstract
The intraflagellar transport (IFT) system is a remarkable molecular machine used by cells to assemble and maintain the cilium, a long organelle extending from eukaryotic cells that gives rise to motility, sensing and signaling. IFT plays a critical role in building the cilium by shuttling structural components and signaling receptors between the ciliary base and tip. To provide effective transport, IFT-A and IFT-B adaptor protein complexes assemble into highly repetitive polymers, called IFT trains, that are powered by the motors kinesin-2 and IFT-dynein to move bidirectionally along the microtubules. This dynamic system must be precisely regulated to shuttle different cargo proteins between the ciliary tip and base. In this Cell Science at a Glance article and the accompanying poster, we discuss the current structural and mechanistic understanding of IFT trains and how they function as macromolecular machines to assemble the structure of the cilium.
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Affiliation(s)
- Mareike A Jordan
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Pfotenhauerstraße 108, 01307 Dresden, Germany
| | - Gaia Pigino
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Pfotenhauerstraße 108, 01307 Dresden, Germany.,Human Technopole, Via Cristina Belgioioso 171, 20157 Milan, Italy
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43
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Etoposide Triggers Cellular Senescence by Inducing Multiple Centrosomes and Primary Cilia in Adrenocortical Tumor Cells. Cells 2021; 10:cells10061466. [PMID: 34208028 PMCID: PMC8230646 DOI: 10.3390/cells10061466] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 06/05/2021] [Accepted: 06/09/2021] [Indexed: 11/17/2022] Open
Abstract
Etoposide (ETO) has been used in treating adrenocortical tumor (ACT) cells. Our previous study showed that ETO inhibits ACT cell growth. In the present study, we show that ETO treatment at IC50 (10 μM) inhibited ACT cell growth by inducing cellular senescence rather than apoptosis. Several markers of cellular senescence, including enlarged nuclei, activated senescence-associated β-galactosidase activity, elevated levels of p53 and p21, and down-regulation of Lamin B1, were observed. We further found that ETO induced multiple centrosomes. The inhibition of multiple centrosomes accomplished by treating cells with either roscovitine or centrinone or through the overexpression of NR5A1/SF-1 alleviated ETO-induced senescence, suggesting that ETO triggered senescence via multiple centrosomes. Primary cilia also played a role in ETO-induced senescence. In the mechanism, DNA-PK-Chk2 signaling was activated by ETO treatment; inhibition of this signaling cascade alleviated multiple ETO-induced centrosomes and primary cilia followed by reducing cellular senescence. In addition to DNA damage signaling, autophagy was also triggered by ETO treatment for centrosomal events and senescence. Importantly, the inactivation of DNA-PK-Chk2 signaling reduced ETO-triggered autophagy; however, the inhibition of autophagy did not affect DNA-PK-Chk2 activation. Thus, ETO activated the DNA-PK-Chk2 cascade to facilitate autophagy. The activated autophagy further induced multiple centrosomes and primary cilia followed by triggering senescence.
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44
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Wang W, Jack BM, Wang HH, Kavanaugh MA, Maser RL, Tran PV. Intraflagellar Transport Proteins as Regulators of Primary Cilia Length. Front Cell Dev Biol 2021; 9:661350. [PMID: 34095126 PMCID: PMC8170031 DOI: 10.3389/fcell.2021.661350] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 04/06/2021] [Indexed: 12/21/2022] Open
Abstract
Primary cilia are small, antenna-like organelles that detect and transduce chemical and mechanical cues in the extracellular environment, regulating cell behavior and, in turn, tissue development and homeostasis. Primary cilia are assembled via intraflagellar transport (IFT), which traffics protein cargo bidirectionally along a microtubular axoneme. Ranging from 1 to 10 μm long, these organelles typically reach a characteristic length dependent on cell type, likely for optimum fulfillment of their specific roles. The importance of an optimal cilia length is underscored by the findings that perturbation of cilia length can be observed in a number of cilia-related diseases. Thus, elucidating mechanisms of cilia length regulation is important for understanding the pathobiology of ciliary diseases. Since cilia assembly/disassembly regulate cilia length, we review the roles of IFT in processes that affect cilia assembly/disassembly, including ciliary transport of structural and membrane proteins, ectocytosis, and tubulin posttranslational modification. Additionally, since the environment of a cell influences cilia length, we also review the various stimuli encountered by renal epithelia in healthy and diseased states that alter cilia length and IFT.
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Affiliation(s)
- Wei Wang
- Department of Anatomy and Cell Biology, The Jared Grantham Kidney Institute, University of Kansas Medical Center, Kansas City, KS, United States
| | - Brittany M Jack
- Department of Anatomy and Cell Biology, The Jared Grantham Kidney Institute, University of Kansas Medical Center, Kansas City, KS, United States
| | - Henry H Wang
- Department of Anatomy and Cell Biology, The Jared Grantham Kidney Institute, University of Kansas Medical Center, Kansas City, KS, United States
| | - Matthew A Kavanaugh
- Department of Anatomy and Cell Biology, The Jared Grantham Kidney Institute, University of Kansas Medical Center, Kansas City, KS, United States
| | - Robin L Maser
- Department of Clinical Laboratory Sciences, The Jared Grantham Kidney Institute, University of Kansas Medical Center, Kansas City, KS, United States
| | - Pamela V Tran
- Department of Anatomy and Cell Biology, The Jared Grantham Kidney Institute, University of Kansas Medical Center, Kansas City, KS, United States
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45
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Atkins M, Týč J, Shafiq S, Ahmed M, Bertiaux E, De Castro Neto AL, Sunter J, Bastin P, Dean SD, Vaughan S. CEP164C regulates flagellum length in stable flagella. J Cell Biol 2021; 220:211523. [PMID: 33165561 PMCID: PMC7833213 DOI: 10.1083/jcb.202001160] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 08/11/2020] [Accepted: 10/20/2020] [Indexed: 12/17/2022] Open
Abstract
Cilia and flagella are required for cell motility and sensing the external environment and can vary in both length and stability. Stable flagella maintain their length without shortening and lengthening and are proposed to “lock” at the end of growth, but molecular mechanisms for this lock are unknown. We show that CEP164C contributes to the locking mechanism at the base of the flagellum in Trypanosoma brucei. CEP164C localizes to mature basal bodies of fully assembled old flagella, but not to growing new flagella, and basal bodies only acquire CEP164C in the third cell cycle after initial assembly. Depletion of CEP164C leads to dysregulation of flagellum growth, with continued growth of the old flagellum, consistent with defects in a flagellum locking mechanism. Inhibiting cytokinesis results in CEP164C acquisition on the new flagellum once it reaches the old flagellum length. These results provide the first insight into the molecular mechanisms regulating flagella growth in cells that must maintain existing flagella while growing new flagella.
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Affiliation(s)
- Madison Atkins
- Biological and Medical Sciences, Oxford Brookes University, Oxford, UK
| | - Jiří Týč
- Biological and Medical Sciences, Oxford Brookes University, Oxford, UK
| | - Shahaan Shafiq
- Biological and Medical Sciences, Oxford Brookes University, Oxford, UK
| | - Manu Ahmed
- Biological and Medical Sciences, Oxford Brookes University, Oxford, UK
| | - Eloïse Bertiaux
- Trypanosome Cell Biology Unit and Institut National de la Santé et de la Recherche Médicale U1201, Institut Pasteur, Paris, France.,Sorbonne Université école doctorale complexité du vivant, Paris, France
| | | | - Jack Sunter
- Biological and Medical Sciences, Oxford Brookes University, Oxford, UK
| | - Philippe Bastin
- Trypanosome Cell Biology Unit and Institut National de la Santé et de la Recherche Médicale U1201, Institut Pasteur, Paris, France
| | | | - Sue Vaughan
- Biological and Medical Sciences, Oxford Brookes University, Oxford, UK
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46
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Sun L, Cui L, Liu Z, Wang Q, Xue Z, Wu M, Sun T, Mao D, Ni J, Pastor-Pareja JC, Liang X. Katanin p60-like 1 sculpts the cytoskeleton in mechanosensory cilia. J Cell Biol 2021; 220:211570. [PMID: 33263729 PMCID: PMC7717695 DOI: 10.1083/jcb.202004184] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 09/28/2020] [Accepted: 10/20/2020] [Indexed: 12/20/2022] Open
Abstract
Mechanoreceptor cells develop a specialized cytoskeleton that plays structural and sensory roles at the site of mechanotransduction. However, little is known about how the cytoskeleton is organized and formed. Using electron tomography and live-cell imaging, we resolve the 3D structure and dynamics of the microtubule-based cytoskeleton in fly campaniform mechanosensory cilia. Investigating the formation of the cytoskeleton, we find that katanin p60-like 1 (kat-60L1), a neuronal type of microtubule-severing enzyme, serves two functions. First, it amplifies the mass of microtubules to form the dense microtubule arrays inside the sensory cilia. Second, it generates short microtubules that are required to build the nanoscopic cytoskeleton at the mechanotransduction site. Additional analyses further reveal the functional roles of Patronin and other potential factors in the local regulatory network. In all, our results characterize the specialized cytoskeleton in fly external mechanosensory cilia at near-molecular resolution and provide mechanistic insights into how it is formed.
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Affiliation(s)
- Landi Sun
- Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Lihong Cui
- Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Zhen Liu
- Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Qixuan Wang
- Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Zhaoyu Xue
- Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Menghua Wu
- Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Tianhui Sun
- Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Decai Mao
- School of Medicine, Tsinghua University, Beijing, China
| | - Jianquan Ni
- School of Medicine, Tsinghua University, Beijing, China
| | - José Carlos Pastor-Pareja
- Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Xin Liang
- Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing, China
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47
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Bauer D, Ishikawa H, Wemmer KA, Hendel NL, Kondev J, Marshall WF. Analysis of biological noise in the flagellar length control system. iScience 2021; 24:102354. [PMID: 33898946 PMCID: PMC8059064 DOI: 10.1016/j.isci.2021.102354] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 03/16/2021] [Accepted: 03/19/2021] [Indexed: 02/06/2023] Open
Abstract
Any proposed mechanism for organelle size control should be able to account not only for average size but also for the variation in size. We analyzed cell-to-cell variation and within-cell variation of length for the two flagella in Chlamydomonas, finding that cell-to-cell variation is dominated by cell size, whereas within-cell variation results from dynamic fluctuations. Fluctuation analysis suggests tubulin assembly is not directly coupled with intraflagellar transport (IFT) and that the observed length fluctuations reflect tubulin assembly and disassembly events involving large numbers of tubulin dimers. Length variation is increased in long-flagella mutants, an effect consistent with theoretical models for flagellar length regulation. Cells with unequal flagellar lengths show impaired swimming but improved gliding, raising the possibility that cells have evolved mechanisms to tune biological noise in flagellar length. Analysis of noise at the level of organelle size provides a way to probe the mechanisms determining cell geometry.
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Affiliation(s)
- David Bauer
- Department of Biochemistry & Biophysics, University of California, San Francisco, 600 16th St., San Francisco, CA, USA
| | - Hiroaki Ishikawa
- Department of Biochemistry & Biophysics, University of California, San Francisco, 600 16th St., San Francisco, CA, USA
| | - Kimberly A. Wemmer
- Department of Biochemistry & Biophysics, University of California, San Francisco, 600 16th St., San Francisco, CA, USA
| | - Nathan L. Hendel
- Department of Biochemistry & Biophysics, University of California, San Francisco, 600 16th St., San Francisco, CA, USA
| | - Jane Kondev
- Department of Physics, Brandeis University, Abelson-Bass-Yalem Building, 97-301, Waltham, MA, USA
| | - Wallace F. Marshall
- Department of Biochemistry & Biophysics, University of California, San Francisco, 600 16th St., San Francisco, CA, USA
- Center for Cellular Construction, University of California, San Francisco, 600 16th St., San Francisco, CA, USA
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48
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Hibbard JVK, Vazquez N, Satija R, Wallingford JB. Protein turnover dynamics suggest a diffusion-to-capture mechanism for peri-basal body recruitment and retention of intraflagellar transport proteins. Mol Biol Cell 2021; 32:1171-1180. [PMID: 33826363 PMCID: PMC8351562 DOI: 10.1091/mbc.e20-11-0717] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Intraflagellar transport (IFT) is essential for construction and maintenance of cilia. IFT proteins concentrate at the basal body where they are thought to assemble into trains and bind cargoes for transport. To study the mechanisms of IFT recruitment to this peri-basal body pool, we quantified protein dynamics of eight IFT proteins, as well as five other basal body localizing proteins using fluorescence recovery after photobleaching in vertebrate multiciliated cells. We found that members of the IFT-A and IFT-B protein complexes show distinct turnover kinetics from other basal body components. Additionally, known IFT subcomplexes displayed shared dynamics, suggesting shared basal body recruitment and/or retention mechanisms. Finally, we evaluated the mechanisms of basal body recruitment by depolymerizing cytosolic MTs, which suggested that IFT proteins are recruited to basal bodies through a diffusion-to-capture mechanism. Our survey of IFT protein dynamics provides new insights into IFT recruitment to basal bodies, a crucial step in ciliogenesis and ciliary signaling.
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Affiliation(s)
- Jaime V K Hibbard
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712
| | - Neftali Vazquez
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712
| | - Rohit Satija
- California Institute of Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720
| | - John B Wallingford
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712
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49
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Barnes CL, Malhotra H, Calvert PD. Compartmentalization of Photoreceptor Sensory Cilia. Front Cell Dev Biol 2021; 9:636737. [PMID: 33614665 PMCID: PMC7889997 DOI: 10.3389/fcell.2021.636737] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 01/07/2021] [Indexed: 12/12/2022] Open
Abstract
Functional compartmentalization of cells is a universal strategy for segregating processes that require specific components, undergo regulation by modulating concentrations of those components, or that would be detrimental to other processes. Primary cilia are hair-like organelles that project from the apical plasma membranes of epithelial cells where they serve as exclusive compartments for sensing physical and chemical signals in the environment. As such, molecules involved in signal transduction are enriched within cilia and regulating their ciliary concentrations allows adaptation to the environmental stimuli. The highly efficient organization of primary cilia has been co-opted by major sensory neurons, olfactory cells and the photoreceptor neurons that underlie vision. The mechanisms underlying compartmentalization of cilia are an area of intense current research. Recent findings have revealed similarities and differences in molecular mechanisms of ciliary protein enrichment and its regulation among primary cilia and sensory cilia. Here we discuss the physiological demands on photoreceptors that have driven their evolution into neurons that rely on a highly specialized cilium for signaling changes in light intensity. We explore what is known and what is not known about how that specialization appears to have driven unique mechanisms for photoreceptor protein and membrane compartmentalization.
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Affiliation(s)
| | | | - Peter D. Calvert
- Department of Ophthalmology and Visual Sciences, Center for Vision Research, SUNY Upstate Medical University, Syracuse, NY, United States
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50
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Datta A, Harbage D, Kondev J. Control of filament length by a depolymerizing gradient. PLoS Comput Biol 2020; 16:e1008440. [PMID: 33275598 PMCID: PMC7744062 DOI: 10.1371/journal.pcbi.1008440] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 12/16/2020] [Accepted: 10/12/2020] [Indexed: 11/19/2022] Open
Abstract
Cells assemble microns-long filamentous structures from protein monomers that are nanometers in size. These structures are often highly dynamic, yet in order for them to function properly, cells maintain them at a precise length. Here we investigate length-dependent depolymerization as a mechanism of length control. This mechanism has been recently proposed for flagellar length control in the single cell organisms Chlamydomonas and Giardia. Length dependent depolymerization can arise from a concentration gradient of a depolymerizing protein, such as kinesin-13 in Giardia, along the length of the flagellum. Two possible scenarios are considered: a linear and an exponential gradient of depolymerizing proteins. We compute analytically the probability distributions of filament lengths for both scenarios and show how these distributions are controlled by key biochemical parameters through a dimensionless number that we identify. In Chlamydomonas cells, the assembly dynamics of its two flagella are coupled via a shared pool of molecular components that are in limited supply, and so we investigate the effect of a limiting monomer pool on the length distributions. Finally, we compare our calculations to experiments. While the computed mean lengths are consistent with observations, the noise is two orders of magnitude smaller than the observed length fluctuations.
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Affiliation(s)
- Arnab Datta
- Department of Physics, Brandeis University, Waltham, Massachusetts, United States of America
| | - David Harbage
- Department of Physics, Brandeis University, Waltham, Massachusetts, United States of America
| | - Jane Kondev
- Department of Physics, Brandeis University, Waltham, Massachusetts, United States of America
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