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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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2
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Murillo-Pineda M, Coto-Cid JM, Romero M, Zorrilla JG, Chinchilla N, Medina-Calzada Z, Varela RM, Juárez-Soto Á, Macías FA, Reales E. Effects of Sesquiterpene Lactones on Primary Cilia Formation (Ciliogenesis). Toxins (Basel) 2023; 15:632. [PMID: 37999495 PMCID: PMC10675014 DOI: 10.3390/toxins15110632] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 10/22/2023] [Accepted: 10/25/2023] [Indexed: 11/25/2023] Open
Abstract
Sesquiterpene lactones (SLs), plant-derived metabolites with broad spectra of biological effects, including anti-tumor and anti-inflammatory, hold promise for drug development. Primary cilia, organelles extending from cell surfaces, are crucial for sensing and transducing extracellular signals essential for cell differentiation and proliferation. Their life cycle is linked to the cell cycle, as cilia assemble in non-dividing cells of G0/G1 phases and disassemble before entering mitosis. Abnormalities in both primary cilia (non-motile cilia) and motile cilia structure or function are associated with developmental disorders (ciliopathies), heart disease, and cancer. However, the impact of SLs on primary cilia remains unknown. This study evaluated the effects of selected SLs (grosheimin, costunolide, and three cyclocostunolides) on primary cilia biogenesis and stability in human retinal pigment epithelial (RPE) cells. Confocal fluorescence microscopy was employed to analyze the effects on primary cilia formation (ciliogenesis), primary cilia length, and stability. The effects on cell proliferation were evaluated by flow cytometry. All SLs disrupted primary cilia formation in the early stages of ciliogenesis, irrespective of starvation conditions or cytochalasin-D treatment, with no effect on cilia length or cell cycle progression. Interestingly, grosheimin stabilized and promoted primary cilia formation under cilia homeostasis and elongation treatment conditions. Thus, SLs have potential as novel drugs for ciliopathies and tumor treatment.
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Affiliation(s)
- Marina Murillo-Pineda
- Research Unit, Biomedical Research and Innovation Institute of Cádiz (INiBICA), Department of Urology, University Hospital of Jerez de la Frontera, 11407 Jerez, Spain; (M.M.-P.); (M.R.); (Z.M.-C.); (Á.J.-S.)
| | - Juan M. Coto-Cid
- Allelopathy Group, Department of Organic Chemistry, Institute of Biomolecules (INBIO), School of Science, University of Cadiz, Campus de Excelencia Internacional (ceiA3), 11510 Puerto Real, Spain; (J.M.C.-C.); (J.G.Z.); (N.C.); (R.M.V.)
- Department of Organic Chemistry, University of Seville, 41012 Seville, Spain
| | - María Romero
- Research Unit, Biomedical Research and Innovation Institute of Cádiz (INiBICA), Department of Urology, University Hospital of Jerez de la Frontera, 11407 Jerez, Spain; (M.M.-P.); (M.R.); (Z.M.-C.); (Á.J.-S.)
| | - Jesús G. Zorrilla
- Allelopathy Group, Department of Organic Chemistry, Institute of Biomolecules (INBIO), School of Science, University of Cadiz, Campus de Excelencia Internacional (ceiA3), 11510 Puerto Real, Spain; (J.M.C.-C.); (J.G.Z.); (N.C.); (R.M.V.)
- Department of Chemical Sciences, University of Naples Federico II, Complesso Universitario Monte S. Angelo, Via Cinthia 4, 80126 Naples, Italy
| | - Nuria Chinchilla
- Allelopathy Group, Department of Organic Chemistry, Institute of Biomolecules (INBIO), School of Science, University of Cadiz, Campus de Excelencia Internacional (ceiA3), 11510 Puerto Real, Spain; (J.M.C.-C.); (J.G.Z.); (N.C.); (R.M.V.)
| | - Zahara Medina-Calzada
- Research Unit, Biomedical Research and Innovation Institute of Cádiz (INiBICA), Department of Urology, University Hospital of Jerez de la Frontera, 11407 Jerez, Spain; (M.M.-P.); (M.R.); (Z.M.-C.); (Á.J.-S.)
| | - Rosa M. Varela
- Allelopathy Group, Department of Organic Chemistry, Institute of Biomolecules (INBIO), School of Science, University of Cadiz, Campus de Excelencia Internacional (ceiA3), 11510 Puerto Real, Spain; (J.M.C.-C.); (J.G.Z.); (N.C.); (R.M.V.)
| | - Álvaro Juárez-Soto
- Research Unit, Biomedical Research and Innovation Institute of Cádiz (INiBICA), Department of Urology, University Hospital of Jerez de la Frontera, 11407 Jerez, Spain; (M.M.-P.); (M.R.); (Z.M.-C.); (Á.J.-S.)
| | - Francisco A. Macías
- Allelopathy Group, Department of Organic Chemistry, Institute of Biomolecules (INBIO), School of Science, University of Cadiz, Campus de Excelencia Internacional (ceiA3), 11510 Puerto Real, Spain; (J.M.C.-C.); (J.G.Z.); (N.C.); (R.M.V.)
| | - Elena Reales
- Research Unit, Biomedical Research and Innovation Institute of Cádiz (INiBICA), Department of Urology, University Hospital of Jerez de la Frontera, 11407 Jerez, Spain; (M.M.-P.); (M.R.); (Z.M.-C.); (Á.J.-S.)
- Allelopathy Group, Department of Organic Chemistry, Institute of Biomolecules (INBIO), School of Science, University of Cadiz, Campus de Excelencia Internacional (ceiA3), 11510 Puerto Real, Spain; (J.M.C.-C.); (J.G.Z.); (N.C.); (R.M.V.)
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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: 2] [Impact Index Per Article: 0.7] [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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Lester WC, Johnson T, Hale B, Serra N, Elgart B, Wang R, Geyer CB, Sperry AO. Aurora a kinase (AURKA) is required for male germline maintenance and regulates sperm motility in the mouse. Biol Reprod 2021; 105:1603-1616. [PMID: 34518881 DOI: 10.1093/biolre/ioab168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 03/12/2021] [Accepted: 09/02/2021] [Indexed: 11/13/2022] Open
Abstract
Aurora A kinase (AURKA) is an important regulator of cell division and is required for assembly of the mitotic spindle. We recently reported the unusual finding that this mitotic kinase is also found on the sperm flagellum. To determine its requirement in spermatogenesis, we generated conditional knockout animals with deletion of the Aurka gene in either spermatogonia or spermatocytes to assess its role in mitotic and postmitotic cells, respectively. Deletion of Aurka in spermatogonia resulted in disappearance of all developing germ cells in the testis, as expected given its vital role in mitotic cell division. Deletion of Aurka in spermatocytes reduced testis size, sperm count, and fertility, indicating disruption of meiosis or an effect on spermiogenesis in developing mice. Interestingly, deletion of Aurka in spermatocytes increased apoptosis in spermatocytes along with an increase in the percentage of sperm with abnormal morphology. Despite the increase in abnormal sperm, sperm from spermatocyte Aurka knockout mice displayed increased progressive motility. In addition, sperm lysate prepared from Aurka knockout animals had decreased protein phosphatase 1 (PP1) activity. Together, our results show that AURKA plays multiple roles in spermatogenesis, from mitotic divisions of spermatogonia to sperm morphology and motility.
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Affiliation(s)
- William C Lester
- Department of Anatomy and Cell Biology at the Brody School of Medicine
| | - Taylor Johnson
- Department of Anatomy and Cell Biology at the Brody School of Medicine.,East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville NC, USA 27834
| | - Ben Hale
- Department of Anatomy and Cell Biology at the Brody School of Medicine.,East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville NC, USA 27834
| | - Nicholas Serra
- Department of Anatomy and Cell Biology at the Brody School of Medicine.,East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville NC, USA 27834
| | - Brian Elgart
- Department of Anatomy and Cell Biology at the Brody School of Medicine
| | - Rong Wang
- Department of Anatomy and Cell Biology at the Brody School of Medicine
| | - Christopher B Geyer
- Department of Anatomy and Cell Biology at the Brody School of Medicine.,East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville NC, USA 27834
| | - Ann O Sperry
- Department of Anatomy and Cell Biology at the Brody School of Medicine
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5
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Power KM, Akella JS, Gu A, Walsh JD, Bellotti S, Morash M, Zhang W, Ramadan YH, Ross N, Golden A, Smith HE, Barr MM, O’Hagan R. Mutation of NEKL-4/NEK10 and TTLL genes suppress neuronal ciliary degeneration caused by loss of CCPP-1 deglutamylase function. PLoS Genet 2020; 16:e1009052. [PMID: 33064774 PMCID: PMC7592914 DOI: 10.1371/journal.pgen.1009052] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 10/28/2020] [Accepted: 08/14/2020] [Indexed: 12/29/2022] Open
Abstract
Ciliary microtubules are subject to post-translational modifications that act as a "Tubulin Code" to regulate motor traffic, binding proteins and stability. In humans, loss of CCP1, a cytosolic carboxypeptidase and tubulin deglutamylating enzyme, causes infantile-onset neurodegeneration. In C. elegans, mutations in ccpp-1, the homolog of CCP1, result in progressive degeneration of neuronal cilia and loss of neuronal function. To identify genes that regulate microtubule glutamylation and ciliary integrity, we performed a forward genetic screen for suppressors of ciliary degeneration in ccpp-1 mutants. We isolated the ttll-5(my38) suppressor, a mutation in a tubulin tyrosine ligase-like glutamylase gene. We show that mutation in the ttll-4, ttll-5, or ttll-11 gene suppressed the hyperglutamylation-induced loss of ciliary dye filling and kinesin-2 mislocalization in ccpp-1 cilia. We also identified the nekl-4(my31) suppressor, an allele affecting the NIMA (Never in Mitosis A)-related kinase NEKL-4/NEK10. In humans, NEK10 mutation causes bronchiectasis, an airway and mucociliary transport disorder caused by defective motile cilia. C. elegans NEKL-4 localizes to the ciliary base but does not localize to cilia, suggesting an indirect role in ciliary processes. This work defines a pathway in which glutamylation, a component of the Tubulin Code, is written by TTLL-4, TTLL-5, and TTLL-11; is erased by CCPP-1; is read by ciliary kinesins; and its downstream effects are modulated by NEKL-4 activity. Identification of regulators of microtubule glutamylation in diverse cellular contexts is important to the development of effective therapies for disorders characterized by changes in microtubule glutamylation. By identifying C. elegans genes important for neuronal and ciliary stability, our work may inform research into the roles of the tubulin code in human ciliopathies and neurodegenerative diseases.
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Affiliation(s)
- Kade M. Power
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, United States of America
| | - Jyothi S. Akella
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, United States of America
| | - Amanda Gu
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, United States of America
| | - Jonathon D. Walsh
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, United States of America
| | - Sebastian Bellotti
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, United States of America
| | - Margaret Morash
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, United States of America
| | - Winnie Zhang
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, United States of America
| | - Yasmin H. Ramadan
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, United States of America
| | - Nicole Ross
- Biology Department, Montclair State University, Montclair, NJ, United States of America
| | - Andy Golden
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Harold E. Smith
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Maureen M. Barr
- Department of Genetics and Human Genetics Institute of New Jersey, Rutgers University, Piscataway, NJ, United States of America
| | - Robert O’Hagan
- Biology Department, Montclair State University, Montclair, NJ, United States of America
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Meyberg R, Perroud PF, Haas FB, Schneider L, Heimerl T, Renzaglia KS, Rensing SA. Characterisation of evolutionarily conserved key players affecting eukaryotic flagellar motility and fertility using a moss model. THE NEW PHYTOLOGIST 2020; 227:440-454. [PMID: 32064607 PMCID: PMC8224819 DOI: 10.1111/nph.16486] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 02/07/2020] [Indexed: 05/18/2023]
Abstract
Defects in flagella/cilia are often associated with infertility and disease. Motile male gametes (sperm cells) are an ancestral eukaryotic trait that has been lost in several lineages like flowering plants. Here, we made use of a phenotypic male fertility difference between two moss (Physcomitrella patens) ecotypes to explore spermatozoid function. We compare genetic and epigenetic variation as well as expression profiles between the Gransden and Reute ecotype to identify a set of candidate genes associated with moss male infertility. We generated a loss-of-function mutant of a coiled-coil domain containing 39 (ccdc39) gene that is part of the flagellar hydin network. Defects in mammal and algal homologues of this gene coincide with a loss of fertility, demonstrating the evolutionary conservation of flagellar function related to male fertility across kingdoms. The Ppccdc39 mutant resembles the Gransden phenotype in terms of male fertility. Potentially, several somatic (epi-)mutations occurred during prolonged vegetative propagation of Gransden, causing regulatory differences of for example the homeodomain transcription factor BELL1. Probably these somatic changes are causative for the observed male fertility defect. We propose that moss spermatozoids might be employed as an easily accessible system to study male infertility of humans and animals in terms of flagellar structure and movement.
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Affiliation(s)
- Rabea Meyberg
- Plant Cell Biology, Faculty of Biology, University of Marburg, Karl-von-Frisch Str. 8, 35043 Marburg, Germany
| | - Pierre-François Perroud
- Plant Cell Biology, Faculty of Biology, University of Marburg, Karl-von-Frisch Str. 8, 35043 Marburg, Germany
| | - Fabian B. Haas
- Plant Cell Biology, Faculty of Biology, University of Marburg, Karl-von-Frisch Str. 8, 35043 Marburg, Germany
| | - Lucas Schneider
- Plant Cell Biology, Faculty of Biology, University of Marburg, Karl-von-Frisch Str. 8, 35043 Marburg, Germany
| | - Thomas Heimerl
- LOEWE Center for Synthetic Microbiology (SYNMIKRO), University of Marburg, Karl-von-Frisch Str. 8, 35043 Marburg, Germany
| | - Karen S. Renzaglia
- Department of Plant Biology, Southern Illinois University, Mail Code 6509, 1125 Lincoln Drive, Carbondale, IL 62901, USA
| | - Stefan A. Rensing
- Plant Cell Biology, Faculty of Biology, University of Marburg, Karl-von-Frisch Str. 8, 35043 Marburg, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Schänzlestraße 18, 79104 Freiburg, Germany
- LOEWE Center for Synthetic Microbiology (SYNMIKRO), University of Marburg, Karl-von-Frisch Str. 8, 35043 Marburg, Germany
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Hansen JN, Kaiser F, Klausen C, Stüven B, Chong R, Bönigk W, Mick DU, Möglich A, Jurisch-Yaksi N, Schmidt FI, Wachten D. Nanobody-directed targeting of optogenetic tools to study signaling in the primary cilium. eLife 2020; 9:e57907. [PMID: 32579112 PMCID: PMC7338050 DOI: 10.7554/elife.57907] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 06/24/2020] [Indexed: 12/17/2022] Open
Abstract
Compartmentalization of cellular signaling forms the molecular basis of cellular behavior. The primary cilium constitutes a subcellular compartment that orchestrates signal transduction independent from the cell body. Ciliary dysfunction causes severe diseases, termed ciliopathies. Analyzing ciliary signaling has been challenging due to the lack of tools to investigate ciliary signaling. Here, we describe a nanobody-based targeting approach for optogenetic tools in mammalian cells and in vivo in zebrafish to specifically analyze ciliary signaling and function. Thereby, we overcome the loss of protein function observed after fusion to ciliary targeting sequences. We functionally localized modifiers of cAMP signaling, the photo-activated adenylyl cyclase bPAC and the light-activated phosphodiesterase LAPD, and the cAMP biosensor mlCNBD-FRET to the cilium. Using this approach, we studied the contribution of spatial cAMP signaling in controlling cilia length. Combining optogenetics with nanobody-based targeting will pave the way to the molecular understanding of ciliary function in health and disease.
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Affiliation(s)
- Jan N Hansen
- Institute of Innate Immunity, Biophysical Imaging, Medical Faculty, University of BonnBonnGermany
| | - Fabian Kaiser
- Institute of Innate Immunity, Biophysical Imaging, Medical Faculty, University of BonnBonnGermany
| | - Christina Klausen
- Institute of Innate Immunity, Biophysical Imaging, Medical Faculty, University of BonnBonnGermany
| | - Birthe Stüven
- Institute of Innate Immunity, Biophysical Imaging, Medical Faculty, University of BonnBonnGermany
| | - Raymond Chong
- Institute of Innate Immunity, Biophysical Imaging, Medical Faculty, University of BonnBonnGermany
| | - Wolfgang Bönigk
- Department of Molecular Sensory Systems, Center of Advanced European Studies and Research (caesar)BonnGermany
| | - David U Mick
- Center for Molecular Signaling (PZMS), Center of Human and Molecular Biology (ZHMB), Saarland University, School of MedicineHomburgGermany
| | - Andreas Möglich
- Lehrstuhl für Biochemie, Universität BayreuthBayreuthGermany
- Research Center for Bio-Macromolecules, Universität BayreuthBayreuthGermany
- Bayreuth Center for Biochemistry & Molecular Biology, Universität BayreuthBayreuthGermany
| | - Nathalie Jurisch-Yaksi
- Kavli Institute for Systems Neuroscience and Centre for Neural Computation, The Faculty of Medicine, Norwegian University of Science and TechnologyTrondheimNorway
- Department of Neurology and Clinical Neurophysiology, St. Olavs University HospitalTrondheimNorway
| | - Florian I Schmidt
- Institute of Innate Immunity, Emmy Noether research group, Medical Faculty, University of BonnBonnGermany
- Core Facility Nanobodies, University of BonnBonnGermany
| | - Dagmar Wachten
- Institute of Innate Immunity, Biophysical Imaging, Medical Faculty, University of BonnBonnGermany
- Research Group Molecular Physiology, Center of Advanced European Studies and Research (caesar)BonnGermany
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Fai TG, Mohapatra L, Kar P, Kondev J, Amir A. Length regulation of multiple flagella that self-assemble from a shared pool of components. eLife 2019; 8:e42599. [PMID: 31596235 PMCID: PMC6863624 DOI: 10.7554/elife.42599] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 10/08/2019] [Indexed: 11/24/2022] Open
Abstract
The single-celled green algae Chlamydomonas reinhardtii with its two flagella-microtubule-based structures of equal and constant lengths-is the canonical model organism for studying size control of organelles. Experiments have identified motor-driven transport of tubulin to the flagella tips as a key component of their length control. Here we consider a class of models whose key assumption is that proteins responsible for the intraflagellar transport (IFT) of tubulin are present in limiting amounts. We show that the limiting-pool assumption is insufficient to describe the results of severing experiments, in which a flagellum is regenerated after it has been severed. Next, we consider an extension of the limiting-pool model that incorporates proteins that depolymerize microtubules. We show that this 'active disassembly' model of flagellar length control explains in quantitative detail the results of severing experiments and use it to make predictions that can be tested in experiments.
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Affiliation(s)
- Thomas G Fai
- Department of MathematicsBrandeis UniversityWalthamUnited States
| | | | - Prathitha Kar
- Paulson School of Engineering and Applied SciencesHarvard UniversityCambridgeUnited States
| | - Jane Kondev
- Department of PhysicsBrandeis UniversityWalthamUnited States
| | - Ariel Amir
- Paulson School of Engineering and Applied SciencesHarvard UniversityCambridgeUnited States
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Maurya AK, Rogers T, Sengupta P. A CCRK and a MAK Kinase Modulate Cilia Branching and Length via Regulation of Axonemal Microtubule Dynamics in Caenorhabditis elegans. Curr Biol 2019; 29:1286-1300.e4. [PMID: 30955935 PMCID: PMC6482063 DOI: 10.1016/j.cub.2019.02.062] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 02/06/2019] [Accepted: 02/28/2019] [Indexed: 02/06/2023]
Abstract
The diverse morphologies of primary cilia are tightly regulated as a function of cell type and cellular state. CCRK- and MAK-related kinases have been implicated in ciliary length control in multiple species, although the underlying mechanisms are not fully understood. Here, we show that in C. elegans, DYF-18/CCRK and DYF-5/MAK act in a cascade to generate the highly arborized cilia morphologies of the AWA olfactory neurons. Loss of kinase function results in dramatically elongated AWA cilia that lack branches. Intraflagellar transport (IFT) motor protein localization, but not velocities, in AWA cilia is altered upon loss of dyf-18. We instead find that axonemal microtubules are decorated by the EBP-2 end-binding protein along their lengths and that the tubulin load is increased and tubulin turnover is reduced in AWA cilia of dyf-18 mutants. Moreover, we show that predicted microtubule-destabilizing mutations in two tubulin subunits, as well as mutations in IFT proteins predicted to disrupt tubulin transport, restore cilia branching and suppress AWA cilia elongation in dyf-18 mutants. Loss of dyf-18 is also sufficient to elongate the truncated rod-like unbranched cilia of the ASH nociceptive neurons in animals carrying a microtubule-destabilizing mutation in a tubulin subunit. We suggest that CCRK and MAK activity tunes cilia length and shape in part via modulation of axonemal microtubule stability, suggesting that similar mechanisms may underlie their roles in ciliary length control in other cell types.
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Affiliation(s)
- Ashish Kumar Maurya
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02454, USA.
| | - Travis Rogers
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02454, USA
| | - Piali Sengupta
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02454, USA.
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10
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Hendel NL, Thomson M, Marshall WF. Diffusion as a Ruler: Modeling Kinesin Diffusion as a Length Sensor for Intraflagellar Transport. Biophys J 2019; 114:663-674. [PMID: 29414712 PMCID: PMC5985012 DOI: 10.1016/j.bpj.2017.11.3784] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 10/30/2017] [Accepted: 11/29/2017] [Indexed: 02/01/2023] Open
Abstract
An important question in cell biology is whether cells are able to measure size, either whole cell size or organelle size. Perhaps cells have an internal chemical representation of size that can be used to precisely regulate growth, or perhaps size is just an accident that emerges due to constraint of nutrients. The eukaryotic flagellum is an ideal model for studying size sensing and control because its linear geometry makes it essentially one-dimensional, greatly simplifying mathematical modeling. The assembly of flagella is regulated by intraflagellar transport (IFT), in which kinesin motors carry cargo adaptors for flagellar proteins along the flagellum and then deposit them at the tip, lengthening the flagellum. The rate at which IFT motors are recruited to begin transport into the flagellum is anticorrelated with the flagellar length, implying some kind of communication between the base and the tip and possibly indicating that cells contain some mechanism for measuring flagellar length. Although it is possible to imagine many complex scenarios in which additional signaling molecules sense length and carry feedback signals to the cell body to control IFT, might the already-known components of the IFT system be sufficient to allow length dependence of IFT? Here we investigate a model in which the anterograde kinesin motors unbind after cargo delivery, diffuse back to the base, and are subsequently reused to power entry of new IFT trains into the flagellum. By mathematically modeling and simulating such a system, we are able to show that the diffusion time of the motors can in principle be sufficient to serve as a proxy for length measurement. We found that the diffusion model can not only achieve a stable steady-state length without the addition of any other signaling molecules or pathways, but also is able to produce the anticorrelation between length and IFT recruitment rate that has been observed in quantitative imaging studies.
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Affiliation(s)
- Nathan L Hendel
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California; Bioinformatics Graduate Group, University of California, San Francisco, San Francisco, California
| | - Matthew Thomson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California
| | - Wallace F Marshall
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California.
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11
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Wang Y, Ren Y, Pan J. Regulation of flagellar assembly and length in
Chlamydomonas
by LF4, a MAPK‐related kinase. FASEB J 2019; 33:6431-6441. [DOI: 10.1096/fj.201802375rr] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Yingrui Wang
- Ministry of Education (MOE) Key Laboratory for Protein ScienceTsinghua‐Peking Center for Life SciencesSchool of Life SciencesTsinghua University Beijing China
| | - Yahui Ren
- Ministry of Education (MOE) Key Laboratory for Protein ScienceTsinghua‐Peking Center for Life SciencesSchool of Life SciencesTsinghua University Beijing China
| | - Junmin Pan
- Ministry of Education (MOE) Key Laboratory for Protein ScienceTsinghua‐Peking Center for Life SciencesSchool of Life SciencesTsinghua University Beijing China
- Laboratory for Marine Biology and BiotechnologyQingdao National Laboratory for Marine Science and Technology Qingdao China
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12
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Liang Y, Zhu X, Wu Q, Pan J. Ciliary Length Sensing Regulates IFT Entry via Changes in FLA8/KIF3B Phosphorylation to Control Ciliary Assembly. Curr Biol 2018; 28:2429-2435.e3. [PMID: 30057303 DOI: 10.1016/j.cub.2018.05.069] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Revised: 04/22/2018] [Accepted: 05/23/2018] [Indexed: 11/24/2022]
Abstract
The length of cilia is robustly regulated [1]. Previous data suggest that cells possess a sensing system to control ciliary length [2-5]. However, the details of the mechanism are currently not known [6, 7]. Such a system requires a mechanism that responds to ciliary length, and consequently, disruption of that response system should alter ciliary length [1]. The assembly rate of cilium mediated by intraflagellar transport (IFT) gradually decreases as the cilium elongates and eventually is balanced by the constant rate of disassembly, at which point cilium elongation stops [8, 9]. Because the rate of IFT entry into the cilium also decreases as the cilium elongates [10], regulation of IFT entry could provide the mechanism for length control. Previously, we showed that phosphorylation of the FLA8/KIF3B subunit of the anterograde kinesin-II IFT motor blocks IFT entry and flagellar assembly in Chlamydomonas [11]. Here, we show in Chlamydomonas that cellular signaling in response to alteration of flagellar length regulates phosphorylation of FLA8/KIF3B, which restricts IFT entry and, thus, flagellar assembly to control flagellar length. Cellular levels of phosphorylated FLA8 (pFLA8) are tightly linked to flagellar length: FLA8 phosphorylation is reduced in cells with short flagella and elevated in cells with long flagella. Depletion of the phosphatases CrPP1 and CrPP6 increases the level of cellular pFLA8, leading to short flagella due to decreased IFT entry. The results demonstrate that ciliary length control is achieved by a cellular sensing system that controls IFT entry through phosphorylation of the anterograde IFT motor.
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Affiliation(s)
- Yinwen Liang
- MOE Key Laboratory of Protein Sciences, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Xin Zhu
- MOE Key Laboratory of Protein Sciences, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Qiong Wu
- MOE Key Laboratory of Protein Sciences, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Junmin Pan
- MOE Key Laboratory of Protein Sciences, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong Province, China.
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13
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Yi P, Xie C, Ou G. The kinases male germ cell-associated kinase and cell cycle-related kinase regulate kinesin-2 motility inCaenorhabditis elegansneuronal cilia. Traffic 2018; 19:522-535. [DOI: 10.1111/tra.12572] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 04/03/2018] [Accepted: 04/06/2018] [Indexed: 12/22/2022]
Affiliation(s)
- Peishan Yi
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences and MOE Key Laboratory for Protein Science; Tsinghua University; Beijing China
| | - Chao Xie
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences and MOE Key Laboratory for Protein Science; Tsinghua University; Beijing China
| | - Guangshuo Ou
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences and MOE Key Laboratory for Protein Science; Tsinghua University; Beijing China
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14
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DeVaul N, Koloustroubis K, Wang R, Sperry AO. A novel interaction between kinase activities in regulation of cilia formation. BMC Cell Biol 2017; 18:33. [PMID: 29141582 PMCID: PMC5688660 DOI: 10.1186/s12860-017-0149-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 11/01/2017] [Indexed: 01/08/2023] Open
Abstract
Background The primary cilium is an extension of the cell membrane that encloses a microtubule-based axoneme. Primary cilia are essential for transmission of environmental cues that determine cell fate. Disruption of primary cilia function is the molecular basis of numerous developmental disorders. Despite their biological importance, the mechanisms governing their assembly and disassembly are just beginning to be understood. Cilia growth and disassembly are essential events when cells exit and reenter into the cell cycle. The kinases never in mitosis-kinase 2 (Nek2) and Aurora A (AurA) act to depolymerize cilia when cells reenter the cell cycle from G0. Results Coexpression of either kinase with its kinase dead companion [AurA with kinase dead Nek2 (Nek2 KD) or Nek2 with kinase dead AurA (AurA KD)] had different effects on cilia depending on whether cilia are growing or shortening. AurA and Nek2 are individually able to shorten cilia when cilia are growing but both are required when cilia are being absorbed. The depolymerizing activity of each kinase is increased when coexpressed with the kinase dead version of the other kinase but only when cilia are assembling. Additionally, the two kinases act additively when cilia are assembling but not disassembling. Inhibition of AurA increases cilia number while inhibition of Nek2 significantly stimulates cilia length. The complex functional relationship between the two kinases reflects their physical interaction. Further, we identify a role for a PP1 binding protein, PPP1R42, in inhibiting Nek2 and increasing ciliation of ARPE-19 cells. Conclusion We have uncovered a novel functional interaction between Nek2 and AurA that is dependent on the growth state of cilia. This differential interdependence reflects opposing regulation when cilia are growing or shortening. In addition to interaction between the kinases to regulate ciliation, the PP1 binding protein PPP1R42 directly inhibits Nek2 independent of PP1 indicating another level of regulation of this kinase. In summary, we demonstrate a complex interplay between Nek2 and AurA kinases in regulation of ciliation in ARPE-19 cells. Electronic supplementary material The online version of this article (10.1186/s12860-017-0149-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Nicole DeVaul
- Laboratory of Biochemistry and Genetics, National Institute of Diabetics and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Katerina Koloustroubis
- Anatomy and Cell Biology, East Carolina University, Brody School of Medicine, Greenville, NC, USA
| | - Rong Wang
- Anatomy and Cell Biology, East Carolina University, Brody School of Medicine, Greenville, NC, USA
| | - Ann O Sperry
- Anatomy and Cell Biology, East Carolina University, Brody School of Medicine, Greenville, NC, USA.
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15
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Ishikawa H, Marshall WF. Testing the time-of-flight model for flagellar length sensing. Mol Biol Cell 2017; 28:3447-3456. [PMID: 28931591 PMCID: PMC5687043 DOI: 10.1091/mbc.e17-06-0384] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 09/08/2017] [Accepted: 09/11/2017] [Indexed: 11/23/2022] Open
Abstract
A combination of quantitative imaging, modeling, and genetics has been used to test a proposed mechanism for measuring the size of an organelle. One way to measure distance is to send a clock out on a train and measure the elapsed time when the train returns. We tested a molecular version of this model as a possible regulator of intraflagellar transport by altering the return speed of the transport machinery and probing the effect on a known length-dependent process. Cilia and flagella are microtubule-based organelles that protrude from the surface of most cells, are important to the sensing of extracellular signals, and make a driving force for fluid flow. Maintenance of flagellar length requires an active transport process known as intraflagellar transport (IFT). Recent studies reveal that the amount of IFT injection negatively correlates with the length of flagella. These observations suggest that a length-dependent feedback regulates IFT. However, it is unknown how cells recognize the length of flagella and control IFT. Several theoretical models try to explain this feedback system. We focused on one of the models, the “time-of-flight” model, which measures the length of flagella on the basis of the travel time of IFT protein in the flagellar compartment. We tested the time-of-flight model using Chlamydomonas dynein mutant cells, which show slower retrograde transport speed. The amount of IFT injection in dynein mutant cells was higher than that in control cells. This observation does not support the prediction of the time-of-flight model and suggests that Chlamydomonas uses another length-control feedback system rather than that described by the time-of-flight model.
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Affiliation(s)
- Hiroaki Ishikawa
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94143
| | - Wallace F Marshall
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94143
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16
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Lechtreck KF, Van De Weghe JC, Harris JA, Liu P. Protein transport in growing and steady-state cilia. Traffic 2017; 18:277-286. [PMID: 28248449 DOI: 10.1111/tra.12474] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 02/22/2017] [Accepted: 02/22/2017] [Indexed: 12/18/2022]
Abstract
Cilia and eukaryotic flagella are threadlike cell extensions with motile and sensory functions. Their assembly requires intraflagellar transport (IFT), a bidirectional motor-driven transport of protein carriers along the axonemal microtubules. IFT moves ample amounts of structural proteins including tubulin into growing cilia likely explaining its critical role for assembly. IFT continues in non-growing cilia contributing to a variety of processes ranging from axonemal maintenance and the export of non-ciliary proteins to cell locomotion and ciliary signaling. Here, we discuss recent data on cues regulating the type, amount and timing of cargo transported by IFT. A regulation of IFT-cargo interactions is critical to establish, maintain and adjust ciliary length, protein composition and function.
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Affiliation(s)
- Karl F Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, Georgia
| | | | | | - Peiwei Liu
- Department of Cellular Biology, University of Georgia, Athens, Georgia
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17
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Roustan V, Bakhtiari S, Roustan PJ, Weckwerth W. Quantitative in vivo phosphoproteomics reveals reversible signaling processes during nitrogen starvation and recovery in the biofuel model organism Chlamydomonas reinhardtii. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:280. [PMID: 29209414 PMCID: PMC5704542 DOI: 10.1186/s13068-017-0949-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 11/01/2017] [Indexed: 05/22/2023]
Abstract
BACKGROUND Nitrogen deprivation and replenishment induces massive changes at the physiological and molecular level in the green alga Chlamydomonas reinhardtii, including reversible starch and lipid accumulation. Stress signal perception and acclimation involves transient protein phosphorylation. This study aims to provide the first experimental phosphoprotein dataset for the adaptation of C. reinhardtii during nitrogen depletion and recovery growth phases and its impact on lipid accumulation. RESULTS To decipher the signaling pathways involved in this dynamic process, we applied a label-free in vivo shotgun phosphoproteomics analysis on nitrogen-depleted and recovered samples. 1227 phosphopeptides belonging to 732 phosphoproteins were identified and quantified. 470 phosphopeptides showed a significant change across the experimental set-up. Multivariate statistics revealed the reversible phosphorylation process and the time/condition-dependent dynamic rearrangement of the phosphoproteome. Protein-protein interaction analysis of differentially regulated phosphoproteins identified protein kinases and phosphatases, such as DYRKP and an AtGRIK1 orthologue, called CDPKK2, as central players in the coordination of translational, photosynthetic, proteomic and metabolomic activity. Phosphorylation of RPS6, ATG13, and NNK1 proteins points toward a specific regulation of the TOR pathway under nitrogen deprivation. Differential phosphorylation pattern of several eukaryotic initiation factor proteins (EIF) suggests a major control on protein translation and turnover. CONCLUSION This work provides the first phosphoproteomics dataset obtained for Chlamydomonas responses to nitrogen availability, revealing multifactorial signaling pathways and their regulatory function for biofuel production. The reproducibility of the experimental set-up allows direct comparison with proteomics and metabolomics datasets and refines therefore the current model of Chlamydomonas acclimation to various nitrogen levels. Integration of physiological, proteomics, metabolomics, and phosphoproteomics data reveals three phases of acclimation to N availability: (i) a rapid response triggering starch accumulation as well as energy metabolism while chloroplast structure is conserved followed by (ii) chloroplast degradation combined with cell autophagy and lipid accumulation and finally (iii) chloroplast regeneration and cell growth activation after nitrogen replenishment. Plastid development seems to be further interconnected with primary metabolism and energy stress signaling in order to coordinate cellular mechanism to nitrogen availability stress.
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Affiliation(s)
- Valentin Roustan
- Department of Ecogenomics and Systems Biology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Shiva Bakhtiari
- Department of Ecogenomics and Systems Biology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Pierre-Jean Roustan
- Department of Ecogenomics and Systems Biology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
| | - Wolfram Weckwerth
- Department of Ecogenomics and Systems Biology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
- Vienna Metabolomics Center (VIME), University of Vienna, Vienna, Austria
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18
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Ludington WB, Ishikawa H, Serebrenik YV, Ritter A, Hernandez-Lopez RA, Gunzenhauser J, Kannegaard E, Marshall WF. A systematic comparison of mathematical models for inherent measurement of ciliary length: how a cell can measure length and volume. Biophys J 2016; 108:1361-1379. [PMID: 25809250 DOI: 10.1016/j.bpj.2014.12.051] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 12/15/2014] [Accepted: 12/19/2014] [Indexed: 10/23/2022] Open
Abstract
Cells control organelle size with great precision and accuracy to maintain optimal physiology, but the mechanisms by which they do so are largely unknown. Cilia and flagella are simple organelles in which a single measurement, length, can represent size. Maintenance of flagellar length requires an active transport process known as intraflagellar transport, and previous measurements suggest that a length-dependent feedback regulates intraflagellar transport. But the question remains: how is a length-dependent signal produced to regulate intraflagellar transport appropriately? Several conceptual models have been suggested, but testing these models quantitatively requires that they be cast in mathematical form. Here, we derive a set of mathematical models that represent the main broad classes of hypothetical size-control mechanisms currently under consideration. We use these models to predict the relation between length and intraflagellar transport, and then compare the predicted relations for each model with experimental data. We find that three models-an initial bolus formation model, an ion current model, and a diffusion-based model-show particularly good agreement with available experimental data. The initial bolus and ion current models give mathematically equivalent predictions for length control, but fluorescence recovery after photobleaching experiments rule out the initial bolus model, suggesting that either the ion current model or a diffusion-based model is more likely correct. The general biophysical principles of the ion current and diffusion-based models presented here to measure cilia and flagellar length can be generalized to measure any membrane-bound organelle volume, such as the nucleus and endoplasmic reticulum.
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Affiliation(s)
- William B Ludington
- Department of Biophysics and Biochemistry, University of California, San Francisco, San Francisco, California
| | - Hiroaki Ishikawa
- Department of Biophysics and Biochemistry, University of California, San Francisco, San Francisco, California
| | - Yevgeniy V Serebrenik
- Department of Biophysics and Biochemistry, University of California, San Francisco, San Francisco, California
| | - Alex Ritter
- Physiology Course, Marine Biological Laboratory, Woods Hole, Massachusetts
| | | | - Julia Gunzenhauser
- Physiology Course, Marine Biological Laboratory, Woods Hole, Massachusetts
| | - Elisa Kannegaard
- Department of Biophysics and Biochemistry, University of California, San Francisco, San Francisco, California
| | - Wallace F Marshall
- Department of Biophysics and Biochemistry, University of California, San Francisco, San Francisco, California.
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19
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Vannuccini E, Paccagnini E, Cantele F, Gentile M, Dini D, Fino F, Diener D, Mencarelli C, Lupetti P. Two classes of short intraflagellar transport train with different 3D structures are present in Chlamydomonas flagella. J Cell Sci 2016; 129:2064-74. [PMID: 27044756 DOI: 10.1242/jcs.183244] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 03/30/2016] [Indexed: 12/18/2022] Open
Abstract
Intraflagellar transport (IFT) is responsible for the bidirectional trafficking of molecular components required for the elongation and maintenance of eukaryotic cilia and flagella. Cargo is transported by IFT 'trains', linear rows of multiprotein particles moved by molecular motors along the axonemal doublets. We have previously described two structurally distinct categories of 'long' and 'short' trains. Here, we analyse the relative number of these trains throughout flagellar regeneration and show that long trains are most abundant at the beginning of flagellar growth whereas short trains gradually increase in number as flagella elongate. These observations are incompatible with the previous hypothesis that short trains are derived solely from the reorganization of long trains at the flagellar tip. We demonstrate with electron tomography the existence of two distinct ultrastructural organizations for the short trains, we name these 'narrow' and 'wide', and provide the first 3D model of the narrow short trains. These trains are characterized by tri-lobed units, which repeat longitudinally every 16 nm and contact protofilament 7 of the B-tubule. Functional implications of the new structural evidence are discussed.
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Affiliation(s)
- Elisa Vannuccini
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Eugenio Paccagnini
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Francesca Cantele
- Dipartimento di Chimica, Università degli Studi di Milano, Via Camillo Golgi 19, 20133 Milan, Italy
| | - Mariangela Gentile
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Daniele Dini
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Federica Fino
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Dennis Diener
- Department of Molecular, Cellular and Developmental Biology, Yale University, 219 Prospect Street, New Haven, CT 06520, USA
| | - Caterina Mencarelli
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Pietro Lupetti
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
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20
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Meng D, Pan J. A NIMA-related kinase, CNK4, regulates ciliary stability and length. Mol Biol Cell 2016; 27:838-47. [PMID: 26764095 PMCID: PMC4803309 DOI: 10.1091/mbc.e15-10-0707] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 12/07/2015] [Accepted: 01/04/2016] [Indexed: 02/02/2023] Open
Abstract
NIMA-related kinases (Nrks or Neks) have emerged as key regulators of ciliogenesis. In human, mutations in Nek1 and Nek8 cause cilia-related disorders. The ciliary functions of Nrks are mostly revealed by genetic studies; however, the underlying mechanisms are not well understood. Here we show that a Chlamydomonas Nrk, CNK4, regulates ciliary stability and length. CNK4 is localized to the basal body region and the flagella. The cnk4-null mutant exhibited long flagella, with formation of flagellar bulges. The flagella gradually became curled at the bulge formation site, leading to flagellar loss. Electron microscopy shows that the curled flagella involved curling and degeneration of axonemal microtubules. cnk4 mutation resulted in flagellar increases of IFT trains, as well as its accumulation at the flagellar bulges. IFT speeds were not affected, however, IFT trains frequently stalled, leading to reduced IFT frequencies. These data are consistent with a model in which CNK4 regulates microtubule dynamics and IFT to control flagellar stability and length.
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Affiliation(s)
- Dan Meng
- MOE Key Laboratory of Protein Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Junmin Pan
- MOE Key Laboratory of Protein Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
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21
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Hu Z, Liang Y, He W, Pan J. Cilia disassembly with two distinct phases of regulation. Cell Rep 2015; 10:1803-10. [PMID: 25801021 DOI: 10.1016/j.celrep.2015.02.044] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 12/30/2014] [Accepted: 02/17/2015] [Indexed: 01/23/2023] Open
Abstract
Cilia and flagella are dynamic organelles that undergo assembly and disassembly during each cell cycle. They are structurally polarized, and the mechanisms by which these organelles are disassembled are incompletely understood. Here, we show that flagellar resorption occurs in two distinct phases of length-dependent regulation. A CDK-like kinase, encoded by flagellar shortening 1 (FLS1), is required for the normal rate of disassembly of only the distal part of the flagellum. Mechanistically, loss of function of FLS1 prevents the initial phosphorylation of CALK, an aurora-like kinase that regulates flagellar shortening, and induces the earlier onset of the inhibitory phosphorylation of CrKinesin13, a microtubule depolymerase, which is involved in flagellar shortening. In addition, CALK and CrKinesin13 phosphorylation can also be induced by the process of flagellar shortening itself, demonstrating an example of cilia-generated signaling not requiring the binding of a ligand or the stimulation of an ion channel.
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22
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Microtubule-depolymerizing kinesins in the regulation of assembly, disassembly, and length of cilia and flagella. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 317:241-65. [PMID: 26008787 DOI: 10.1016/bs.ircmb.2015.01.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Defects in ciliary assembly, maintenance, and signaling are associated with various human diseases and developmental disorders, termed ciliopathies. Eukaryotic flagella and cilia (interchangeable terms) are microtubule-based organelles. Thus, microtubule dynamics and microtubule-dependent transport are predicted to affect the structural integrity and functionality of cilia profoundly. Kinesin-2 is well known for its role in intraflagellar transport to transport ciliary precursors and signaling molecules. Recently, microtubule-depolymerizing kinesins found in kinesin-8, -13, and -14A families have emerged as regulators of cilia. We first discuss ciliary kinesins identified in the flagellar or ciliary proteome, and then focus on the function and regulation of microtubule-depolymerizing kinesins. Lastly, we review the recent advances of microtubule-depolymerizing kinesins in controlling ciliary assembly, disassembly, and length.
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23
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Craft JM, Harris JA, Hyman S, Kner P, Lechtreck KF. Tubulin transport by IFT is upregulated during ciliary growth by a cilium-autonomous mechanism. ACTA ACUST UNITED AC 2015; 208:223-37. [PMID: 25583998 PMCID: PMC4298693 DOI: 10.1083/jcb.201409036] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In Chlamydomonas cilia, IFT concentrates soluble tubulin by regulating IFT train occupancy and thereby promotes elongation of axonemal microtubules. The assembly of the axoneme, the structural scaffold of cilia and flagella, requires translocation of a vast quantity of tubulin into the growing cilium, but the mechanisms that regulate the targeting, quantity, and timing of tubulin transport are largely unknown. In Chlamydomonas, GFP-tagged α-tubulin enters cilia as an intraflagellar transport (IFT) cargo and by diffusion. IFT-based transport of GFP-tubulin is elevated in growing cilia and IFT trains carry more tubulin. Cells possessing both nongrowing and growing cilia selectively target GFP-tubulin into the latter. The preferential delivery of tubulin boosts the concentration of soluble tubulin in the matrix of growing versus steady-state cilia. Cilia length mutants show abnormal kinetics of tubulin transport. We propose that cells regulate the extent of occupancy of IFT trains by tubulin cargoes. During ciliary growth, IFT concentrates soluble tubulin in cilia and thereby promotes elongation of the axonemal microtubules.
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Affiliation(s)
- Julie M Craft
- Department of Cellular Biology and College of Engineering, University of Georgia, Athens, GA 30602
| | - J Aaron Harris
- Department of Cellular Biology and College of Engineering, University of Georgia, Athens, GA 30602
| | - Sebastian Hyman
- Department of Cellular Biology and College of Engineering, University of Georgia, Athens, GA 30602
| | - Peter Kner
- Department of Cellular Biology and College of Engineering, University of Georgia, Athens, GA 30602
| | - Karl F Lechtreck
- Department of Cellular Biology and College of Engineering, University of Georgia, Athens, GA 30602
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Liang Y, Pang Y, Wu Q, Hu Z, Han X, Xu Y, Deng H, Pan J. FLA8/KIF3B Phosphorylation Regulates Kinesin-II Interaction with IFT-B to Control IFT Entry and Turnaround. Dev Cell 2014; 30:585-97. [DOI: 10.1016/j.devcel.2014.07.019] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 07/15/2014] [Accepted: 07/23/2014] [Indexed: 11/28/2022]
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25
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Bhogaraju S, Weber K, Engel BD, Lechtreck KF, Lorentzen E. Getting tubulin to the tip of the cilium: One IFT train, many different tubulin cargo-binding sites? Bioessays 2014; 36:463-7. [DOI: 10.1002/bies.201400007] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Sagar Bhogaraju
- Department of Structural Cell Biology; Max-Planck-Institute of Biochemistry; Martinsried Germany
| | - Kristina Weber
- Department of Structural Cell Biology; Max-Planck-Institute of Biochemistry; Martinsried Germany
| | - Benjamin D. Engel
- Department of Molecular Structural Biology; Max-Planck-Institute of Biochemistry; Martinsried Germany
| | | | - Esben Lorentzen
- Department of Structural Cell Biology; Max-Planck-Institute of Biochemistry; Martinsried Germany
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26
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Abstract
Cilia and flagella are surface-exposed, finger-like organelles whose core consists of a microtubule (MT)-based axoneme that grows from a modified centriole, the basal body. Cilia are found on the surface of many eukaryotic cells and play important roles in cell motility and in coordinating a variety of signaling pathways during growth, development, and tissue homeostasis. Defective cilia have been linked to a number of developmental disorders and diseases, collectively called ciliopathies. Cilia are dynamic organelles that assemble and disassemble in tight coordination with the cell cycle. In most cells, cilia are assembled during growth arrest in a multistep process involving interaction of vesicles with appendages present on the distal end of mature centrioles, and addition of tubulin and other building blocks to the distal tip of the basal body and growing axoneme; these building blocks are sorted through a region at the cilium base known as the ciliary necklace, and then transported via intraflagellar transport (IFT) along the axoneme toward the tip for assembly. After assembly, the cilium frequently continues to turn over and incorporate tubulin at its distal end in an IFT-dependent manner. Prior to cell division, the cilia are usually resorbed to liberate centrosomes for mitotic spindle pole formation. Here, we present an overview of the main cytoskeletal structures associated with cilia and centrioles with emphasis on the MT-associated appendages, fibers, and filaments at the cilium base and tip. The composition and possible functions of these structures are discussed in relation to cilia assembly, disassembly, and length regulation.
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Affiliation(s)
- Lotte B Pedersen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark.
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Hilton LK, Gunawardane K, Kim JW, Schwarz MC, Quarmby LM. The kinases LF4 and CNK2 control ciliary length by feedback regulation of assembly and disassembly rates. Curr Biol 2013; 23:2208-2214. [PMID: 24184104 DOI: 10.1016/j.cub.2013.09.038] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 09/12/2013] [Accepted: 09/12/2013] [Indexed: 11/29/2022]
Abstract
BACKGROUND Many of the diverse functions of cilia depend upon tight control of their length. Steady-state length reflects a balance between rates of ciliary assembly and disassembly, two parameters likely controlled by a length sensor of unknown identity or mechanism. RESULTS A null mutation in Chlamydomonas CNK2, a member of the evolutionarily conserved family of NIMA-related kinases, reveals feedback regulation of assembly and disassembly rates. cnk2-1 mutant cells have a mild long-flagella (lf) phenotype as a consequence of reduced rates of flagellar disassembly. This is in contrast to the strong lf mutant lf4-7, which exhibits an aberrantly high rate of assembly. Cells carrying both mutations have even longer flagella than lf4-7 single mutants do. In addition to their high rate of assembly, lf4-7 mutants have a CNK2-dependent increase in disassembly rate. Finally, cnk2-1 cells have a decreased rate of turnover of flagellar subunits at the tip of the flagellum, demonstrating that the effects on disassembly are compensated by a reduced rate of assembly. CONCLUSIONS We propose a model wherein CNK2 and LF4 modulate rates of disassembly and assembly respectively in a feedback loop that is activated when flagella exceed optimal length.
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Affiliation(s)
- Laura K Hilton
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Kavisha Gunawardane
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Joo Wan Kim
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Marianne C Schwarz
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Lynne M Quarmby
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada.
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Liang Y, Pan J. Regulation of flagellar biogenesis by a calcium dependent protein kinase in Chlamydomonas reinhardtii. PLoS One 2013; 8:e69902. [PMID: 23936117 PMCID: PMC3723818 DOI: 10.1371/journal.pone.0069902] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 06/17/2013] [Indexed: 11/23/2022] Open
Abstract
Chlamydomonas reinhardtii, a bi-flagellated green alga, is a model organism for studies of flagella or cilia related activities including cilia-based signaling, flagellar motility and flagellar biogenesis. Calcium has been shown to be a key regulator of these cellular processes whereas the signaling pathways linking calcium to these cellular functions are less understood. Calcium-dependent protein kinases (CDPKs), which are present in plants but not in animals, are also present in ciliated microorganisms which led us to examine their possible functions and mechanisms in flagellar related activities. By in silico analysis of Chlamydomonas genome we have identified 14 CDPKs and studied one of the flagellar localized CDPKs – CrCDPK3. CrCDPK3 was a protein of 485 amino acids and predicted to have a protein kinase domain at the N-terminus and four EF-hand motifs at the C-terminus. In flagella, CrCDPK3 was exclusively localized in the membrane matrix fraction and formed an unknown 20 S protein complex. Knockdown of CrCDPK3 expression by using artificial microRNA did not affect flagellar motility as well as flagellar adhesion and mating. Though flagellar shortening induced by treatment with sucrose or sodium pyrophosphate was not affected in RNAi strains, CrCDPK3 increased in the flagella, and pre-formed protein complex was disrupted. During flagellar regeneration, CrCDPK3 also increased in the flagella. When extracellular calcium was lowered to certain range by the addition of EGTA after deflagellation, flagellar regeneration was severely affected in RNAi cells compared with wild type cells. In addition, during flagellar elongation induced by LiCl, RNAi cells exhibited early onset of bulbed flagella. This work expands new functions of CDPKs in flagellar activities by showing involvement of CrCDPK3 in flagellar biogenesis in Chlamydomonas.
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Affiliation(s)
- Yinwen Liang
- Ministry of Environment Key Laboratory of Protein Science, School of Life Sciences, Tsinghua University, Beijing, China
| | - Junmin Pan
- Ministry of Environment Key Laboratory of Protein Science, School of Life Sciences, Tsinghua University, Beijing, China
- * E-mail: (JP)
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Activation loop phosphorylation of a protein kinase is a molecular marker of organelle size that dynamically reports flagellar length. Proc Natl Acad Sci U S A 2013; 110:12337-42. [PMID: 23836633 DOI: 10.1073/pnas.1302364110] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Specification of organelle size is crucial for cell function, yet we know little about the molecular mechanisms that report and regulate organelle growth and steady-state dimensions. The biflagellated green alga Chlamydomonas requires continuous-length feedback to integrate the multiple events that support flagellar assembly and disassembly and at the same time maintain the sensory and motility functions of the organelle. Although several length mutants have been characterized, the requisite molecular reporter of length has not been identified. Previously, we showed that depletion of Chlamydomonas aurora-like protein kinase CALK inhibited flagellar disassembly and that a gel-shift-associated phosphorylation of CALK marked half-length flagella during flagellar assembly. Here, we show that phosphorylation of CALK on T193, a consensus phosphorylation site on the activation loop required for kinase activity, is distinct from the gel-shift-associated phosphorylation and is triggered when flagellar shortening is induced, thereby implicating CALK protein kinase activity in the shortening arm of length control. Moreover, CALK phosphorylation on T193 is dynamically related to flagellar length. It is reduced in cells with short flagella, elevated in the long flagella mutant, lf4, and dynamically tracks length during both flagellar assembly and flagellar disassembly in WT, but not in lf4. Thus, phosphorylation of CALK in its activation loop is implicated in the disassembly arm of a length feedback mechanism and is a continuous and dynamic molecular marker of flagellar length during both assembly and disassembly.
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Hochegger H, Hégarat N, Pereira-Leal JB. Aurora at the pole and equator: overlapping functions of Aurora kinases in the mitotic spindle. Open Biol 2013; 3:120185. [PMID: 23516109 PMCID: PMC3718339 DOI: 10.1098/rsob.120185] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The correct assembly and timely disassembly of the mitotic spindle is crucial for the propagation of the genome during cell division. Aurora kinases play a central role in orchestrating bipolar spindle establishment, chromosome alignment and segregation. In most eukaryotes, ranging from amoebas to humans, Aurora activity appears to be required both at the spindle pole and the kinetochore, and these activities are often split between two different Aurora paralogues, termed Aurora A and B. Polar and equatorial functions of Aurora kinases have generally been considered separately, with Aurora A being mostly involved in centrosome dynamics, whereas Aurora B coordinates kinetochore attachment and cytokinesis. However, double inactivation of both Aurora A and B results in a dramatic synergy that abolishes chromosome segregation. This suggests that these two activities jointly coordinate mitotic progression. Accordingly, recent evidence suggests that Aurora A and B work together in both spindle assembly in metaphase and disassembly in anaphase. Here, we provide an outlook on these shared functions of the Auroras, discuss the evolution of this family of mitotic kinases and speculate why Aurora kinase activity may be required at both ends of the spindle microtubules.
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Affiliation(s)
- Helfrid Hochegger
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton, UK.
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31
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Wang L, Piao T, Cao M, Qin T, Huang L, Deng H, Mao T, Pan J. Flagellar regeneration requires cytoplasmic microtubule depolymerization and kinesin-13. J Cell Sci 2013; 126:1531-40. [PMID: 23418346 DOI: 10.1242/jcs.124255] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
In ciliated cells, two types of microtubules can be categorized: cytoplasmic and axonemal. It has been shown that axonemal tubulins come from a 'cytoplasmic pool' during cilia regeneration. However, the identity and regulation of this 'pool' is not understood. Previously, we have shown that Chlamydomonas kinesin-13 (CrKin13) is phosphorylated during flagellar regeneration, and required for proper flagellar assembly. In the present study, we show that CrKin13 regulates depolymerization of cytoplasmic microtubules to control flagellar regeneration. After flagellar loss and before flagellar regeneration, cytoplasmic microtubules were quickly depolymerized, which was evidenced by the appearance of sparse and shorter microtubule arrays and increased free tubulins in the cell body. Knockdown of CrKin13 expression by RNA interference inhibited depolymerization of cytoplasmic microtubules and impaired flagellar regeneration. In vitro assay showed that CrKin13 possessed microtubule depolymerization activity. CrKin13 underwent phosphorylation during microtubule depolymerization, and phosphorylation induced targeting of CrKin13 to microtubules. The phosphorylation of CrKin13 occurred at residues S100, T469 and S522 as determined by mass spectrometry. Abrogation of CrKin13 phosphorylation at S100 but not at other residues by inducing point mutation prevented CrKin13 targeting to microtubules. We propose that CrKin13 depolymerizes cytoplasmic microtubules to provide tubulin precursors for flagellar regeneration.
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Affiliation(s)
- Liang Wang
- Protein Science Laboratory of the Ministry of Education, School of Life Sciences, Tsinghua University, Beijing 100084, China
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32
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Tam LW, Ranum PT, Lefebvre PA. CDKL5 regulates flagellar length and localizes to the base of the flagella in Chlamydomonas. Mol Biol Cell 2013; 24:588-600. [PMID: 23283985 PMCID: PMC3583663 DOI: 10.1091/mbc.e12-10-0718] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Two mutations in LF5, which encodes a protein kinase orthologous to human CDKL5, cause abnormally long flagella in Chlamydomonas. The localization of LF5p to the very proximal region of flagella in WT cells is regulated by three other LF gene products, which make up the cytoplasmic length regulatory complex. The length of Chlamydomonas flagella is tightly regulated. Mutations in four genes—LF1, LF2, LF3, and LF4—cause cells to assemble flagella up to three times wild-type length. LF2 and LF4 encode protein kinases. Here we describe a new gene, LF5, in which null mutations cause cells to assemble flagella of excess length. The LF5 gene encodes a protein kinase very similar in sequence to the protein kinase CDKL5. In humans, mutations in this kinase cause a severe form of juvenile epilepsy. The LF5 protein localizes to a unique location: the proximal 1 μm of the flagella. The proximal localization of the LF5 protein is lost when genes that make up the proteins in the cytoplasmic length regulatory complex (LRC)—LF1, LF2, and LF3—are mutated. In these mutants LF5p becomes localized either at the distal tip of the flagella or along the flagellar length, indicating that length regulation involves, at least in part, control of LF5p localization by the LRC.
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Affiliation(s)
- Lai-Wa Tam
- Department of Plant Biology, University of Minnesota, St. Paul, MN 55108, USA
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33
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Lehti-Shiu MD, Shiu SH. Diversity, classification and function of the plant protein kinase superfamily. Philos Trans R Soc Lond B Biol Sci 2012; 367:2619-39. [PMID: 22889912 DOI: 10.1098/rstb.2012.0003] [Citation(s) in RCA: 202] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Eukaryotic protein kinases belong to a large superfamily with hundreds to thousands of copies and are components of essentially all cellular functions. The goals of this study are to classify protein kinases from 25 plant species and to assess their evolutionary history in conjunction with consideration of their molecular functions. The protein kinase superfamily has expanded in the flowering plant lineage, in part through recent duplications. As a result, the flowering plant protein kinase repertoire, or kinome, is in general significantly larger than other eukaryotes, ranging in size from 600 to 2500 members. This large variation in kinome size is mainly due to the expansion and contraction of a few families, particularly the receptor-like kinase/Pelle family. A number of protein kinases reside in highly conserved, low copy number families and often play broadly conserved regulatory roles in metabolism and cell division, although functions of plant homologues have often diverged from their metazoan counterparts. Members of expanded plant kinase families often have roles in plant-specific processes and some may have contributed to adaptive evolution. Nonetheless, non-adaptive explanations, such as kinase duplicate subfunctionalization and insufficient time for pseudogenization, may also contribute to the large number of seemingly functional protein kinases in plants.
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Affiliation(s)
- Melissa D Lehti-Shiu
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
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34
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Ai X, Liang Q, Luo M, Zhang K, Pan J, Luo G. Controlling gas/liquid exchange using microfluidics for real-time monitoring of flagellar length in living Chlamydomonas at the single-cell level. LAB ON A CHIP 2012; 12:4516-22. [PMID: 22968631 DOI: 10.1039/c2lc40638a] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Chlamydomonas reinhardtii is widely used for studying cilia/flagella, organelles important for human health and disease. In situ monitoring of flagellar assembly/disassembly kinetics in single living cells has been difficult with conventional methods because of time-consuming media exchange and the requirement of whole cell fixation. Here, we develop a PDMS/glass hybrid microfluidic device for real-time tracking of flagellar length in single living cells of Chlamydomonas. Media exchange is precisely controlled by sequential gas-liquid plugs and complete medium replacement occurs within seconds. Rapid medium exchange allows the capture of transient flagellar dynamics. We show that Chlamydomonas cells respond to acidic medium exchange and deflagellate. However, the two flagella may shed asynchronously. After subsequent medium exchange, cells regenerate full-length flagella. Cells are also induced to shorten their flagella after being exposed to extracellular stimuli. The long-term kinetics of flagellar regeneration and disassembly for the whole cell population on the chip are comparable to those from conventional methods; however, individual cells display non-uniform response kinetics. We also find that flagellar growth rate is dependent on flagellar length. This device provides a potential platform to continuously monitor molecular activities associated with changes in flagellar length and to capture transient molecular changes upon flagellar loss, and initiation of flagellar assembly/disassembly.
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Affiliation(s)
- Xiaoni Ai
- Beijing Key Laboratory for Microanalytical Methods and Instrumentation, Department of Chemistry, Tsinghua University, Beijing, 100084, China
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35
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Ludington WB, Shi LZ, Zhu Q, Berns MW, Marshall WF. Organelle size equalization by a constitutive process. Curr Biol 2012; 22:2173-9. [PMID: 23084989 DOI: 10.1016/j.cub.2012.09.040] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 08/20/2012] [Accepted: 09/24/2012] [Indexed: 11/16/2022]
Abstract
How cells control organelle size is an elusive problem. Two predominant models for size control can be distinguished: (1) induced control, where organelle genesis, maintenance, and disassembly are three separate programs that are activated in response to size change, and (2) constitutive control, where stable size results from the balance between continuous organelle assembly and disassembly. The problem has been studied in Chlamydomonas reinhardtii because the flagella are easy to measure, their size changes only in the length dimension, and the genetics are comparable to yeast. Length dynamics in Chlamydomonas flagella are quite robust: they maintain a length of about 12 μm and recover from amputation in about 90 min with a growth rate that decreases smoothly to zero as the length approaches 12 μm. Despite a wealth of experimental studies, existing data are consistent with both induced and constitutive control models for flagella. Here we developed novel microfluidic trapping and laser microsurgery techniques in Chlamydomonas to distinguish between length control models by measuring the two flagella on a single cell as they equilibrate after amputation of a single flagellum. The results suggest that cells equalize flagellar length by constitutive control.
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Affiliation(s)
- William B Ludington
- Department of Biochemistry, University of California, San Francisco, CA 94122, USA
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36
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Abstract
Cells have developed ways to sense and control the size of their organelles. Size-sensing mechanisms range from direct measurements provided by dedicated reporters to indirect functional readouts, and they are used to modify organelle size under both normal and stress conditions. Organelle size can also be controlled in the absence of an identifiable size sensor. Studies on flagella have dissected principles of size sensing and control, and it will be exciting to see how these principles apply to other organelles.
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Affiliation(s)
- Yee-Hung M Chan
- Department of Biochemistry and Biophysics, UCSF Center for Systems and Synthetic Biology, University of California, San Francisco, San Francisco, CA 94158, USA.
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37
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Gupta A, Diener DR, Sivadas P, Rosenbaum JL, Yang P. The versatile molecular complex component LC8 promotes several distinct steps of flagellar assembly. ACTA ACUST UNITED AC 2012; 198:115-26. [PMID: 22753897 PMCID: PMC3392930 DOI: 10.1083/jcb.201111041] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
LC8 is present in various molecular complexes. However, its role in these complexes remains unclear. We discovered that although LC8 is a subunit of the radial spoke (RS) complex in Chlamydomonas flagella, it was undetectable in the RS precursor that is converted into the mature RS at the tip of elongating axonemes. Interestingly, LC8 dimers bound in tandem to the N-terminal region of a spoke phosphoprotein, RS protein 3 (RSP3), that docks RSs to axonemes. LC8 enhanced the binding of RSP3 N-terminal fragments to purified axonemes. Likewise, the N-terminal fragments extracted from axonemes contained LC8 and putative spoke-docking proteins. Lastly, perturbations of RSP3's LC8-binding sites resulted in asynchronous flagella with hypophosphorylated RSP3 and defective associations between LC8, RSs, and axonemes. We propose that at the tip of flagella, an array of LC8 dimers binds to RSP3 in RS precursors, triggering phosphorylation, stalk base formation, and axoneme targeting. These multiple effects shed new light on fundamental questions about LC8-containing complexes and axoneme assembly.
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Affiliation(s)
- Anjali Gupta
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53201, USA
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38
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Goehring NW, Hyman AA. Organelle growth control through limiting pools of cytoplasmic components. Curr Biol 2012; 22:R330-9. [PMID: 22575475 DOI: 10.1016/j.cub.2012.03.046] [Citation(s) in RCA: 142] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The critical importance of controlling the size and number of intracellular organelles has led to a variety of mechanisms for regulating the formation and growth of cellular structures. In this review, we explore a class of mechanisms for organelle growth control that rely primarily on the cytoplasm as a 'limiting pool' of available material. These mechanisms are based on the idea that, as organelles grow, they incorporate subunits from the cytoplasm. If this subunit pool is limited, organelle growth will lead to depletion of subunits from the cytoplasm. Free subunit concentration therefore provides a measure of the number of incorporated subunits and thus the current size of the organelle. Because organelle growth rates are typically a function of subunit concentration, cytoplasmic depletion links organelle size, free subunit concentration, and growth rates, ensuring that as the organelle grows, its rate of growth slows. Thus, a limiting cytoplasmic pool provides a powerful mechanism for size-dependent regulation of growth without recourse to active mechanisms to measure size or modulate growth rates. Variations of this general idea allow not only for size control, but also cell-size-dependent scaling of cellular structures, coordination of growth between similar structures within a cell, and the enforcement of singularity in structure formation, when only a single copy of a structure is desired. Here, we review several examples of such mechanisms in cellular processes as diverse as centriole duplication, centrosome and nuclear size control, cell polarity, and growth of flagella.
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Affiliation(s)
- Nathan W Goehring
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany.
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39
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Abdul-Majeed S, Moloney BC, Nauli SM. Mechanisms regulating cilia growth and cilia function in endothelial cells. Cell Mol Life Sci 2012; 69:165-73. [PMID: 21671118 PMCID: PMC11115144 DOI: 10.1007/s00018-011-0744-0] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 05/19/2011] [Accepted: 05/30/2011] [Indexed: 12/22/2022]
Abstract
The primary cilium is an important sensory organelle present in most mammalian cells. Our current studies aim at examining intracellular molecules that regulate cilia length and/or cilia function in vitro and ex vivo. For the first time, we show that intracellular cAMP and cAMP-dependent protein kinase (PKA) regulate both cilia length and function in vascular endothelial cells. Although calcium-dependent protein kinase modulates cilia length, it does not play a significant role in cilia function. Cilia length regulation also involves mitogen-activated protein kinase (MAPK), protein phosphatase-1 (PP-1), and cofilin. Furthermore, cofilin regulates cilia length through actin rearrangement. Overall, our study suggests that the molecular interactions between cilia function and length can be independent of one another. Although PKA regulates both cilia length and function, changes in cilia length by MAPK, PP-1, or cofilin do not have a direct correlation to changes in cilia function. We propose that cilia length and function are regulated by distinct, yet complex intertwined signaling pathways.
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Affiliation(s)
- Shakila Abdul-Majeed
- Department of Medicinal and Biological Chemistry, The University of Toledo, Toledo, OH 43614 USA
| | - Bryan C. Moloney
- Department of Medicine, The University of Toledo, Toledo, OH 43614 USA
| | - Surya M. Nauli
- Department of Medicinal and Biological Chemistry, The University of Toledo, Toledo, OH 43614 USA
- Department of Medicine, The University of Toledo, Toledo, OH 43614 USA
- Department of Pharmacology, The University of Toledo, Health Science Campus, HEB 274, 3000 Arlington Ave., MS 1015, Toledo, OH 43614 USA
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Avasthi P, Marshall WF. Stages of ciliogenesis and regulation of ciliary length. Differentiation 2011; 83:S30-42. [PMID: 22178116 DOI: 10.1016/j.diff.2011.11.015] [Citation(s) in RCA: 170] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 11/30/2011] [Accepted: 11/30/2011] [Indexed: 12/25/2022]
Abstract
Cilia and flagella are highly conserved eukaryotic microtubule-based organelles that protrude from the surface of most mammalian cells. These structures require large protein complexes and motors for distal addition of tubulin and extension of the ciliary membrane. In order for ciliogenesis to occur, coordination of many processes must take place. An intricate concert of cell cycle regulation, vesicular trafficking, and ciliary extension must all play out with accurate timing to produce a cilium. Here, we review the stages of ciliogenesis as well as regulation of the length of the assembled cilium. Regulation of ciliogenesis during cell cycle progression centers on centrioles, from which cilia extend upon maturation into basal bodies. Centriole maturation involves a shift from roles in cell division to cilium nucleation via migration to the cell surface and docking at the plasma membrane. Docking is dependent on a variety of proteinaceous structures, termed distal appendages, acquired by the mother centriole. Ciliary elongation by the process of intraflagellar transport (IFT) ensues. Direct modification of ciliary structures, as well as modulation of signal transduction pathways, play a role in maintenance of the cilium. All of these stages are tightly regulated to produce a cilium of the right size at the right time. Finally, we discuss the implications of abnormal ciliogenesis and ciliary length control in human disease as well as some open questions.
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Affiliation(s)
- Prachee Avasthi
- Department of Biochemistry & Biophysics, University of California GH-N372F Genentech Hall, Box 2200, UCSF, 600 16th St. San Francisco, CA 94158, USA
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