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Whole-Organism Developmental Expression Profiling Identifies RAB-28 as a Novel Ciliary GTPase Associated with the BBSome and Intraflagellar Transport. PLoS Genet 2016; 12:e1006469. [PMID: 27930654 PMCID: PMC5145144 DOI: 10.1371/journal.pgen.1006469] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 11/08/2016] [Indexed: 01/18/2023] Open
Abstract
Primary cilia are specialised sensory and developmental signalling devices extending from the surface of most eukaryotic cells. Defects in these organelles cause inherited human disorders (ciliopathies) such as retinitis pigmentosa and Bardet-Biedl syndrome (BBS), frequently affecting many physiological and developmental processes across multiple organs. Cilium formation, maintenance and function depend on intracellular transport systems such as intraflagellar transport (IFT), which is driven by kinesin-2 and IFT-dynein motors and regulated by the Bardet-Biedl syndrome (BBS) cargo-adaptor protein complex, or BBSome. To identify new cilium-associated genes, we employed the nematode C. elegans, where ciliogenesis occurs within a short timespan during late embryogenesis when most sensory neurons differentiate. Using whole-organism RNA-Seq libraries, we discovered a signature expression profile highly enriched for transcripts of known ciliary proteins, including FAM-161 (FAM161A orthologue), CCDC-104 (CCDC104), and RPI-1 (RP1/RP1L1), which we confirm are cilium-localised in worms. From a list of 185 candidate ciliary genes, we uncover orthologues of human MAP9, YAP, CCDC149, and RAB28 as conserved cilium-associated components. Further analyses of C. elegans RAB-28, recently associated with autosomal-recessive cone-rod dystrophy, reveal that this small GTPase is exclusively expressed in ciliated neurons where it dynamically associates with IFT trains. Whereas inactive GDP-bound RAB-28 displays no IFT movement and diffuse localisation, GTP-bound (activated) RAB-28 concentrates at the periciliary membrane in a BBSome-dependent manner and undergoes bidirectional IFT. Functional analyses reveal that whilst cilium structure, sensory function and IFT are seemingly normal in a rab-28 null allele, overexpression of predicted GDP or GTP locked variants of RAB-28 perturbs cilium and sensory pore morphogenesis and function. Collectively, our findings present a new approach for identifying ciliary proteins, and unveil RAB28, a GTPase most closely related to the BBS protein RABL4/IFT27, as an IFT-associated cargo with BBSome-dependent cell autonomous and non-autonomous functions at the ciliary base. Ciliopathies are genetic disorders that arise from loss or mutation of genes that encode proteins which play roles in the biology of cilia, organelles found on most of the cells in the human body. Ciliopathy-associated ailments include–but are not limited to–kidney dysfunction, blindness, skeletal abnormalities, as well as brain disorders. Although a great number of cilium-targeted proteins are known, it is thought that a large proportion remain unidentified. Here, we use a developmental gene expression series to discover novel cilia genes in the nematode Caenorhabditis elegans. We present several cilium-localised proteins resulting from our analysis, including RAB-28, a GTPase previously implicated in the degenerative eye disease known as cone-rod dystrophy. Through live videomicroscopy, we show that RAB-28 undergoes bidirectional transport within the cilium. A RAB-28 inactivating mutation results in loss of transport, while an activating mutation results in stronger localisation at the ciliary base and robust transport, although overexpression results in a variety of cilia-related defects. Both the wild type and activating mutant proteins require the Bardet-Biedl Syndrome-related complex of proteins for their transport, linking RAB-28 to an established ciliary transport machinery.
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102
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Abstract
Many animal cells assemble single cilia involved in motile and/or sensory functions. In contrast, multiciliated cells (MCCs) assemble up to 300 motile cilia that beat in a coordinate fashion to generate a directional fluid flow. In the human airways, the brain, and the oviduct, MCCs allow mucus clearance, cerebrospinal fluid circulation, and egg transportation, respectively. Impairment of MCC function leads to chronic respiratory infections and increased risks of hydrocephalus and female infertility. MCC differentiation during development or repair involves the activation of a regulatory cascade triggered by the inhibition of Notch activity in MCC progenitors. The downstream events include the simultaneous assembly of a large number of basal bodies (BBs)-from which cilia are nucleated-in the cytoplasm of the differentiating MCCs, their migration and docking at the plasma membrane associated to an important remodeling of the actin cytoskeleton, and the assembly and polarization of motile cilia. The direction of ciliary beating is coordinated both within cells and at the tissue level by a combination of planar polarity cues affecting BB position and hydrodynamic forces that are both generated and sensed by the cilia. Herein, we review the mechanisms controlling the specification and differentiation of MCCs and BB assembly and organization at the apical surface, as well as ciliary assembly and coordination in MCCs.
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Affiliation(s)
- Alice Meunier
- Institut de Biologie de l'Ecole Normale Supérieure, Institut National de la Santé et de la Recherche Médicale U1024, Centre National de la Recherche Scientifique UMR8197, 75005 Paris, France
| | - Juliette Azimzadeh
- Institut Jacques Monod, Centre National de la Recherche Scientifique UMR7592, Université Paris-Diderot, 75013 Paris, France
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103
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Vertii A, Hehnly H, Doxsey S. The Centrosome, a Multitalented Renaissance Organelle. Cold Spring Harb Perspect Biol 2016; 8:8/12/a025049. [PMID: 27908937 DOI: 10.1101/cshperspect.a025049] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The centrosome acts as a microtubule-organizing center (MTOC) from the G1 to G2 phases of the cell cycle; it can mature into a spindle pole during mitosis and/or transition into a cilium by elongating microtubules (MTs) from the basal body on cell differentiation or cell cycle arrest. New studies hint that the centrosome functions in more than MT organization. For instance, it has recently been shown that a specific substructure of the centrosome-the mother centriole appendages-are required for the recycling of endosomes back to the plasma membrane. This alone could have important implications for a renaissance in our understanding of the development of primary cilia, endosome recycling, and the immune response. Here, we review newly identified roles for the centrosome in directing membrane traffic, the immunological synapse, and the stress response.
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Affiliation(s)
- Anastassiia Vertii
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605
| | - Heidi Hehnly
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605
| | - Stephen Doxsey
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605
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104
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Stoetzel C, Bär S, De Craene JO, Scheidecker S, Etard C, Chicher J, Reck JR, Perrault I, Geoffroy V, Chennen K, Strähle U, Hammann P, Friant S, Dollfus H. A mutation in VPS15 (PIK3R4) causes a ciliopathy and affects IFT20 release from the cis-Golgi. Nat Commun 2016; 7:13586. [PMID: 27882921 PMCID: PMC5123056 DOI: 10.1038/ncomms13586] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 10/18/2016] [Indexed: 11/25/2022] Open
Abstract
Ciliopathies are a group of diseases that affect kidney and retina among other organs. Here, we identify a missense mutation in PIK3R4 (phosphoinositide 3-kinase regulatory subunit 4, named VPS15) in a family with a ciliopathy phenotype. Besides being required for trafficking and autophagy, we show that VPS15 regulates primary cilium length in human fibroblasts, as well as ciliary processes in zebrafish. Furthermore, we demonstrate its interaction with the golgin GM130 and its localization to the Golgi. The VPS15-R998Q patient mutation impairs Golgi trafficking functions in humanized yeast cells. Moreover, in VPS15-R998Q patient fibroblasts, the intraflagellar transport protein IFT20 is not localized to vesicles trafficking to the cilium but is restricted to the Golgi. Our findings suggest that at the Golgi, VPS15 and GM130 form a protein complex devoid of VPS34 to ensure the IFT20-dependent sorting and transport of membrane proteins from the cis-Golgi to the primary cilium. VPS15 is known as a VPS34-associated protein that functions in intracellular trafficking and autophagy. Here the authors identify a role for VPS15 in ciliopathy and ciliary phenotypes, and show that it interacts with GM130 and functions in IFT20-dependent cis-Golgi to cilium trafficking.
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Affiliation(s)
- Corinne Stoetzel
- Medical Genetics Laboratory, INSERM U1112, Institute of Medical Genetics of Alsace, University of Strasbourg, Strasbourg Medical School, 67000 Strasbourg, France
| | - Séverine Bär
- Department of Molecular and Cellular Genetics, UMR7156, Centre National de Recherche Scientifique (CNRS), Université de Strasbourg, 67084 Strasbourg, France
| | - Johan-Owen De Craene
- Department of Molecular and Cellular Genetics, UMR7156, Centre National de Recherche Scientifique (CNRS), Université de Strasbourg, 67084 Strasbourg, France
| | - Sophie Scheidecker
- Medical Genetics Laboratory, INSERM U1112, Institute of Medical Genetics of Alsace, University of Strasbourg, Strasbourg Medical School, 67000 Strasbourg, France
| | - Christelle Etard
- Institut für Toxikologie und Genetik, Campus Nord, Karlsruher Institut für Technologie, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein Leopoldshafen, Germany
| | - Johana Chicher
- Institut de Biologie Moléculaire et Cellulaire (IBMC), Plateforme Protéomique Strasbourg-Esplanade, CNRS FRC1589, 67084 Strasbourg, France
| | - Jennifer R Reck
- Department of Molecular and Cellular Genetics, UMR7156, Centre National de Recherche Scientifique (CNRS), Université de Strasbourg, 67084 Strasbourg, France
| | - Isabelle Perrault
- Laboratory of Genetics in Ophthalmology, INSERM UMR1163, Institut Imagine, Université Paris Descartes Sorbonne Paris Cité, Hôpital Necker, 75015 Paris, France
| | - Véronique Geoffroy
- Medical Genetics Laboratory, INSERM U1112, Institute of Medical Genetics of Alsace, University of Strasbourg, Strasbourg Medical School, 67000 Strasbourg, France
| | - Kirsley Chennen
- Medical Genetics Laboratory, INSERM U1112, Institute of Medical Genetics of Alsace, University of Strasbourg, Strasbourg Medical School, 67000 Strasbourg, France
| | - Uwe Strähle
- Institut für Toxikologie und Genetik, Campus Nord, Karlsruher Institut für Technologie, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein Leopoldshafen, Germany
| | - Philippe Hammann
- Institut de Biologie Moléculaire et Cellulaire (IBMC), Plateforme Protéomique Strasbourg-Esplanade, CNRS FRC1589, 67084 Strasbourg, France
| | - Sylvie Friant
- Department of Molecular and Cellular Genetics, UMR7156, Centre National de Recherche Scientifique (CNRS), Université de Strasbourg, 67084 Strasbourg, France
| | - Hélène Dollfus
- Medical Genetics Laboratory, INSERM U1112, Institute of Medical Genetics of Alsace, University of Strasbourg, Strasbourg Medical School, 67000 Strasbourg, France.,Centre de Référence pour les affections rares en génétique ophtalmologique, CARGO, Filière SENSGENE, Hôpitaux Universitaires de Strasbourg, 67091 Strasbourg, France
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105
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Dehlink E, Hogg C, Carr SB, Bush A. Clinical phenotype and current diagnostic criteria for primary ciliary dyskinesia. Expert Rev Respir Med 2016; 10:1163-1175. [DOI: 10.1080/17476348.2016.1242414] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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106
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Boubakri M, Chaya T, Hirata H, Kajimura N, Kuwahara R, Ueno A, Malicki J, Furukawa T, Omori Y. Loss of ift122, a Retrograde Intraflagellar Transport (IFT) Complex Component, Leads to Slow, Progressive Photoreceptor Degeneration Due to Inefficient Opsin Transport. J Biol Chem 2016; 291:24465-24474. [PMID: 27681595 DOI: 10.1074/jbc.m116.738658] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 09/21/2016] [Indexed: 11/06/2022] Open
Abstract
In the retina, aberrant opsin transport from cell bodies to outer segments leads to retinal degenerative diseases such as retinitis pigmentosa. Opsin transport is facilitated by the intraflagellar transport (IFT) system that mediates the bidirectional movement of proteins within cilia. In contrast to functions of the anterograde transport executed by IFT complex B (IFT-B), the precise functions of the retrograde transport mediated by IFT complex A (IFT-A) have not been well studied in photoreceptor cilia. Here, we analyzed developing zebrafish larvae carrying a null mutation in ift122 encoding a component of IFT-A. ift122 mutant larvae show unexpectedly mild phenotypes, compared with those of mutants defective in IFT-B. ift122 mutants exhibit a slow onset of progressive photoreceptor degeneration mainly after 7 days post-fertilization. ift122 mutant larvae also develop cystic kidney but not curly body, both of which are typically observed in various ciliary mutants. ift122 mutants display a loss of cilia in the inner ear hair cells and nasal pit epithelia. Loss of ift122 causes disorganization of outer segment discs. Ectopic accumulation of an IFT-B component, ift88, is observed in the ift122 mutant photoreceptor cilia. In addition, pulse-chase experiments using GFP-opsin fusion proteins revealed that ift122 is required for the efficient transport of opsin and the distal elongation of outer segments. These results show that IFT-A is essential for the efficient transport of outer segment proteins, including opsin, and for the survival of retinal photoreceptor cells, rendering the ift122 mutant a unique model for human retinal degenerative diseases.
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Affiliation(s)
- Meriam Boubakri
- From the Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, and
| | - Taro Chaya
- From the Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, and; PRESTO, Japan Science and Technology Agency (JST), 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hiromi Hirata
- the Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara 252-5258, Japan
| | - Naoko Kajimura
- the Research Center for Ultrahigh Voltage Electron Microscopy, Osaka University, 7-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan, and
| | - Ryusuke Kuwahara
- the Research Center for Ultrahigh Voltage Electron Microscopy, Osaka University, 7-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan, and
| | - Akiko Ueno
- From the Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, and
| | - Jarema Malicki
- the Bateson Centre, Department of Biomedical Science, University of Sheffield, Firth Court Western Bank, Sheffield S10 2TN, United Kingdom
| | - Takahisa Furukawa
- From the Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, and
| | - Yoshihiro Omori
- From the Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, and; PRESTO, Japan Science and Technology Agency (JST), 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan,.
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107
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Vieillard J, Paschaki M, Duteyrat JL, Augière C, Cortier E, Lapart JA, Thomas J, Durand B. Transition zone assembly and its contribution to axoneme formation in Drosophila male germ cells. J Cell Biol 2016; 214:875-89. [PMID: 27646273 PMCID: PMC5037411 DOI: 10.1083/jcb.201603086] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 08/26/2016] [Indexed: 01/04/2023] Open
Abstract
Ciliary transition zone (TZ) assembly is complex and incompletely understood. Vieillard et al. show that Drosophila Cby and Dila cooperate to assemble the TZ and membrane cap, which, together with microtubule remodeling by kinesin-13, is required for axoneme formation in male germ cells. The ciliary transition zone (TZ) is a complex structure found at the cilia base. Defects in TZ assembly are associated with human ciliopathies. In most eukaryotes, three protein complexes (CEP290, NPHP, and MKS) cooperate to build the TZ. We show that in Drosophila melanogaster, mild TZ defects are observed in the absence of MKS components. In contrast, Cby and Azi1 cooperate to build the TZ by acting upstream of Cep290 and MKS components. Without Cby and Azi1, centrioles fail to form the TZ, precluding sensory cilia assembly, and no ciliary membrane cap associated with sperm ciliogenesis is made. This ciliary cap is critical to recruit the tubulin-depolymerizing kinesin Klp59D, required for regulation of axonemal growth. Our results show that Drosophila TZ assembly in sensory neurons and male germ cells involves cooperative actions of Cby and Dila. They further reveal that temporal control of membrane cap assembly by TZ components and microtubule elongation by kinesin-13 is required for axoneme formation in male germ cells.
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Affiliation(s)
- Jennifer Vieillard
- Université Claude Bernard Lyon 1, Institut National de la Santé et de la Recherche Médicale U1217, Institut NeuroMyoGène, Centre National de la Recherche Scientifique UMR 5310, F-69100 Lyon, France
| | - Marie Paschaki
- Université Claude Bernard Lyon 1, Institut National de la Santé et de la Recherche Médicale U1217, Institut NeuroMyoGène, Centre National de la Recherche Scientifique UMR 5310, F-69100 Lyon, France
| | - Jean-Luc Duteyrat
- Université Claude Bernard Lyon 1, Institut National de la Santé et de la Recherche Médicale U1217, Institut NeuroMyoGène, Centre National de la Recherche Scientifique UMR 5310, F-69100 Lyon, France
| | - Céline Augière
- Université Claude Bernard Lyon 1, Institut National de la Santé et de la Recherche Médicale U1217, Institut NeuroMyoGène, Centre National de la Recherche Scientifique UMR 5310, F-69100 Lyon, France
| | - Elisabeth Cortier
- Université Claude Bernard Lyon 1, Institut National de la Santé et de la Recherche Médicale U1217, Institut NeuroMyoGène, Centre National de la Recherche Scientifique UMR 5310, F-69100 Lyon, France
| | - Jean-André Lapart
- Université Claude Bernard Lyon 1, Institut National de la Santé et de la Recherche Médicale U1217, Institut NeuroMyoGène, Centre National de la Recherche Scientifique UMR 5310, F-69100 Lyon, France
| | - Joëlle Thomas
- Université Claude Bernard Lyon 1, Institut National de la Santé et de la Recherche Médicale U1217, Institut NeuroMyoGène, Centre National de la Recherche Scientifique UMR 5310, F-69100 Lyon, France
| | - Bénédicte Durand
- Université Claude Bernard Lyon 1, Institut National de la Santé et de la Recherche Médicale U1217, Institut NeuroMyoGène, Centre National de la Recherche Scientifique UMR 5310, F-69100 Lyon, France
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108
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Abstract
Most motile and all non-motile (also known as primary) eukaryotic cilia possess microtubule-based axonemes that are assembled at the cell surface to form hair-like or more elaborate compartments endowed with motility and/or signaling functions. Such compartmentalized ciliogenesis depends on the core intraflagellar transport (IFT) machinery and the associated Bardet-Biedl syndrome complex (BBSome) for dynamic delivery of ciliary components. The transition zone (TZ), an ultrastructurally complex barrier or 'gate' at the base of cilia, also contributes to the formation of compartmentalized cilia. Yet, some ciliated protists do not have IFT components and, like some metazoan spermatozoa, use IFT-independent mechanisms to build axonemes exposed to the cytosol. Moreover, various ciliated protists lack TZ components, whereas Drosophila sperm surprisingly requires the activity of dynamically localized TZ proteins for cytosolic ciliogenesis. Here, we discuss the various ways eukaryotes use IFT and/or TZ proteins to generate the wide assortment of compartmentalized and cytosolic cilia observed in nature. Consideration of the different ciliogenesis pathways allows us to propose how three types of cytosol-exposed cilia (primary, secondary and tertiary), including cilia found in the human sperm proximal segment, are likely generated by evolutionary derivations of compartmentalized ciliogenesis.
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109
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Pedersen LB, Mogensen JB, Christensen ST. Endocytic Control of Cellular Signaling at the Primary Cilium. Trends Biochem Sci 2016; 41:784-797. [DOI: 10.1016/j.tibs.2016.06.002] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 06/03/2016] [Accepted: 06/07/2016] [Indexed: 01/20/2023]
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110
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Siller SS, Burke MC, Li FQ, Takemaru KI. Chibby functions to preserve normal ciliary morphology through the regulation of intraflagellar transport in airway ciliated cells. Cell Cycle 2016; 14:3163-72. [PMID: 26266958 DOI: 10.1080/15384101.2015.1080396] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Airway cilia provide the coordinated motive force for mucociliary transport, which prevents the accumulation of mucus, debris, pollutants, and bacteria in our respiratory tracts. As airway cilia are constantly exposed to the environment and, hence, are an integral component of the pathogenesis of several congenital and chronic pulmonary disorders, it is necessary to understand the molecular mechanisms that control ciliated cell differentiation and ciliogenesis. We have previously reported that loss of the basal body protein Chibby (Cby) results in chronic upper airway infection in mice due to a significant reduction in the number of airway cilia. In the present work, we demonstrate that Cby is required for normal ciliary structure and proper distribution of proteins involved in the bidirectional intraflagellar transport (IFT) system, which consists of 2 distinct sub-complexes, IFT-A and IFT-B, and is essential for ciliary biogenesis and maintenance. In fully differentiated ciliated cells, abnormal paddle-like cilia with dilated ciliary tips are observed in Cby-/- airways and primary cultures of mouse tracheal epithelial cells (MTECs). In addition, IFT88, an IFT-B sub-complex protein, robustly accumulates within the dilated tips of both multicilia in Cby-/- MTECs and primary cilia in Cby-/- mouse embryonic fibroblasts (MEFs). Furthermore, we show that only IFT-B components, including IFT20 and IFT57, but not IFT-A and Bardet-Biedl syndrome (BBS) proteins, amass with IFT88 in these distended tips in Cby-/- ciliated cells. Taken together, our findings suggest that Cby plays a role in the proper distribution of IFT particles to preserve normal ciliary morphology in airway ciliated cells.
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Affiliation(s)
- Saul S Siller
- a Medical Scientist Training Program; Stony Brook University; Stony Brook , NY USA.,b Graduate Program in Molecular and Cellular Pharmacology; Stony Brook University; Stony Brook , NY USA.,c Department of Pharmacological Sciences ; Stony Brook University; Stony Brook , NY USA
| | - Michael C Burke
- a Medical Scientist Training Program; Stony Brook University; Stony Brook , NY USA.,d Graduate Program in Genetics; Stony Brook University; Stony Brook , NY USA
| | - Feng-Qian Li
- b Graduate Program in Molecular and Cellular Pharmacology; Stony Brook University; Stony Brook , NY USA.,c Department of Pharmacological Sciences ; Stony Brook University; Stony Brook , NY USA
| | - Ken-Ichi Takemaru
- a Medical Scientist Training Program; Stony Brook University; Stony Brook , NY USA.,b Graduate Program in Molecular and Cellular Pharmacology; Stony Brook University; Stony Brook , NY USA.,c Department of Pharmacological Sciences ; Stony Brook University; Stony Brook , NY USA.,d Graduate Program in Genetics; Stony Brook University; Stony Brook , NY USA
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111
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Pratt MB, Titlow JS, Davis I, Barker AR, Dawe HR, Raff JW, Roque H. Drosophila sensory cilia lacking MKS proteins exhibit striking defects in development but only subtle defects in adults. J Cell Sci 2016; 129:3732-3743. [PMID: 27577095 PMCID: PMC5087661 DOI: 10.1242/jcs.194621] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 08/19/2016] [Indexed: 01/05/2023] Open
Abstract
Cilia are conserved organelles that have important motility, sensory and signalling roles. The transition zone (TZ) at the base of the cilium is crucial for cilia function, and defects in several TZ proteins are associated with human congenital ciliopathies such as nephronophthisis (NPHP) and Meckel-Gruber syndrome (MKS). In several species, MKS and NPHP proteins form separate complexes that cooperate with Cep290 to assemble the TZ, but flies seem to lack core components of the NPHP module. We show that MKS proteins in flies are spatially separated from Cep290 at the TZ, and that flies mutant for individual MKS genes fail to recruit other MKS proteins to the TZ, whereas Cep290 seems to be recruited normally. Although there are abnormalities in microtubule and membrane organisation in developing MKS mutant cilia, these defects are less apparent in adults, where sensory cilia and sperm flagella seem to function quite normally. Thus, localising MKS proteins to the cilium or flagellum is not essential for viability or fertility in flies.
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Affiliation(s)
- Metta B Pratt
- The Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Joshua S Titlow
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Ilan Davis
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Amy R Barker
- Centre for Microvascular Research, William Harvey Research Institute, Queen Mary University of London, London EC1M 6BQ, UK
| | - Helen R Dawe
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK
| | - Jordan W Raff
- The Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Helio Roque
- The Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
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112
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Timbers TA, Garland SJ, Mohan S, Flibotte S, Edgley M, Muncaster Q, Au V, Li-Leger E, Rosell FI, Cai J, Rademakers S, Jansen G, Moerman DG, Leroux MR. Accelerating Gene Discovery by Phenotyping Whole-Genome Sequenced Multi-mutation Strains and Using the Sequence Kernel Association Test (SKAT). PLoS Genet 2016; 12:e1006235. [PMID: 27508411 PMCID: PMC4980031 DOI: 10.1371/journal.pgen.1006235] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 07/11/2016] [Indexed: 11/25/2022] Open
Abstract
Forward genetic screens represent powerful, unbiased approaches to uncover novel components in any biological process. Such screens suffer from a major bottleneck, however, namely the cloning of corresponding genes causing the phenotypic variation. Reverse genetic screens have been employed as a way to circumvent this issue, but can often be limited in scope. Here we demonstrate an innovative approach to gene discovery. Using C. elegans as a model system, we used a whole-genome sequenced multi-mutation library, from the Million Mutation Project, together with the Sequence Kernel Association Test (SKAT), to rapidly screen for and identify genes associated with a phenotype of interest, namely defects in dye-filling of ciliated sensory neurons. Such anomalies in dye-filling are often associated with the disruption of cilia, organelles which in humans are implicated in sensory physiology (including vision, smell and hearing), development and disease. Beyond identifying several well characterised dye-filling genes, our approach uncovered three genes not previously linked to ciliated sensory neuron development or function. From these putative novel dye-filling genes, we confirmed the involvement of BGNT-1.1 in ciliated sensory neuron function and morphogenesis. BGNT-1.1 functions at the trans-Golgi network of sheath cells (glia) to influence dye-filling and cilium length, in a cell non-autonomous manner. Notably, BGNT-1.1 is the orthologue of human B3GNT1/B4GAT1, a glycosyltransferase associated with Walker-Warburg syndrome (WWS). WWS is a multigenic disorder characterised by muscular dystrophy as well as brain and eye anomalies. Together, our work unveils an effective and innovative approach to gene discovery, and provides the first evidence that B3GNT1-associated Walker-Warburg syndrome may be considered a ciliopathy. Model organisms are useful tools for uncovering new genes involved in a biological process via genetic screens. Such an approach is powerful, but suffers from drawbacks that can slow down gene discovery. In forward genetics screens, difficult-to-map phenotypes present daunting challenges, and whole-genome coverage can be equally challenging for reverse genetic screens where typically only a single gene’s function is assayed per strain. Here, we show a different approach which includes positive aspects of forward (high-coverage, randomly-induced mutations) and reverse genetics (prior knowledge of gene disruption) to accelerate gene discovery. We paired a whole-genome sequenced multi-mutation C. elegans library with a rare-variant associated test to rapidly identify genes associated with a phenotype of interest: defects in sensory neurons bearing sensory organelles called cilia, via a simple dye-filling assay to probe the form and function of these cells. We found two well characterised dye-filling genes and three genes, not previously linked to ciliated sensory neuron development or function, that were associated with dye-filling defects. We reveal that disruption of one of these (BGNT-1.1), whose human orthologue is associated with Walker-Warburg syndrome, results in abrogated uptake of dye and cilia length defects. We believe that our novel approach is useful for any organism with a small genome that can be quickly sequenced and where many mutant strains can be easily isolated and phenotyped, such as Drosophila and Arabidopsis.
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Affiliation(s)
- Tiffany A. Timbers
- Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Stephanie J. Garland
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Swetha Mohan
- Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Stephane Flibotte
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Mark Edgley
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Quintin Muncaster
- Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Vinci Au
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Erica Li-Leger
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Federico I. Rosell
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jerry Cai
- Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
| | | | - Gert Jansen
- Department of Cell Biology, Erasmus MC, Rotterdam, The Netherlands
| | - Donald G. Moerman
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Michel R. Leroux
- Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
- * E-mail:
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113
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Penga J, Wang T, Huc J, Wang Y, Chen J. Constructing Networks of Organelle Functional Modules in Arabidopsis. Curr Genomics 2016; 17:427-438. [PMID: 28479871 PMCID: PMC5320545 DOI: 10.2174/1389202917666160726151048] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2015] [Revised: 05/30/2015] [Accepted: 06/05/2015] [Indexed: 11/22/2022] Open
Abstract
With the rapid accumulation of gene expression data, gene functional module identification has become a widely used approach in functional analysis. However, tools to identify organelle functional modules and analyze their relationships are still missing. We present a soft thresholding approach to construct networks of functional modules using gene expression datasets, in which nodes are strongly co-expressed genes that encode proteins residing in the same subcellular localization, and links represent strong inter-module connections. Our algorithm has three steps. First, we identify functional modules by analyzing gene expression data. Next, we use a self-adaptive approach to construct a mixed network of functional modules and genes. Finally, we link functional modules that are tightly connected in the mixed network. Analysis of experimental data from Arabidopsis demonstrates that our approach is effective in improving the interpretability of high-throughput transcriptomic data and inferring function of unknown genes.
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Affiliation(s)
- Jiajie Penga
- School of Computer Science, Northwestern Polytechnical University, Xi'an, P.R. China.,Department of Energy Plant Research Lab, Michigan State University, East Lansing, USA
| | - Tao Wang
- School of Computer Science, Northwestern Polytechnical University, Xi'an, P.R. China
| | - Jianping Huc
- Department of Energy Plant Research Lab, Michigan State University, East Lansing, USA.,Department of Plant Biology, Michigan State University, East Lansing, USA
| | - Yadong Wang
- School of Computer Science, Northwestern Polytechnical University, Xi'an, P.R. China
| | - Jin Chen
- Department of Energy Plant Research Lab, Michigan State University, East Lansing, USA.,Department of Computer Science and Engineering, Michigan State University, East Lansing, USA
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114
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Katoh Y, Terada M, Nishijima Y, Takei R, Nozaki S, Hamada H, Nakayama K. Overall Architecture of the Intraflagellar Transport (IFT)-B Complex Containing Cluap1/IFT38 as an Essential Component of the IFT-B Peripheral Subcomplex. J Biol Chem 2016; 291:10962-75. [PMID: 26980730 PMCID: PMC4900248 DOI: 10.1074/jbc.m116.713883] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 03/14/2016] [Indexed: 01/22/2023] Open
Abstract
Intraflagellar transport (IFT) is essential for assembly and maintenance of cilia and flagella as well as ciliary motility and signaling. IFT is mediated by multisubunit complexes, including IFT-A, IFT-B, and the BBSome, in concert with kinesin and dynein motors. Under high salt conditions, purified IFT-B complex dissociates into a core subcomplex composed of at least nine subunits and at least five peripherally associated proteins. Using the visible immunoprecipitation assay, which we recently developed as a convenient protein-protein interaction assay, we determined the overall architecture of the IFT-B complex, which can be divided into core and peripheral subcomplexes composed of 10 and 6 subunits, respectively. In particular, we identified TTC26/IFT56 and Cluap1/IFT38, neither of which was included with certainty in previous models of the IFT-B complex, as integral components of the core and peripheral subcomplexes, respectively. Consistent with this, a ciliogenesis defect of Cluap1-deficient mouse embryonic fibroblasts was rescued by exogenous expression of wild-type Cluap1 but not by mutant Cluap1 lacking the binding ability to other IFT-B components. The detailed interaction map as well as comparison of subcellular localization of IFT-B components between wild-type and Cluap1-deficient cells provides insights into the functional relevance of the architecture of the IFT-B complex.
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Affiliation(s)
- Yohei Katoh
- From the Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Masaya Terada
- From the Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yuya Nishijima
- From the Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Ryota Takei
- From the Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Shohei Nozaki
- From the Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hiroshi Hamada
- the Developmental Genetics Group, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan, and the Center for Developmental Biology, RIKEN, Chuou-ku, Kobe 650-0047, Japan
| | - Kazuhisa Nakayama
- From the Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan,
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115
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Loucks CM, Bialas NJ, Dekkers MPJ, Walker DS, Grundy LJ, Li C, Inglis PN, Kida K, Schafer WR, Blacque OE, Jansen G, Leroux MR. PACRG, a protein linked to ciliary motility, mediates cellular signaling. Mol Biol Cell 2016; 27:2133-44. [PMID: 27193298 PMCID: PMC4927285 DOI: 10.1091/mbc.e15-07-0490] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 05/09/2016] [Indexed: 01/15/2023] Open
Abstract
Cilia are cellular projections that can be motile to generate fluid flow or nonmotile to enable signaling. Both forms are based on shared components, and proteins involved in ciliary motility, like PACRG, may also function in ciliary signaling. Caenorhabditis elegans PACRG acts in a subset of nonmotile cilia to influence a learning behavior and promote longevity. Cilia are microtubule-based organelles that project from nearly all mammalian cell types. Motile cilia generate fluid flow, whereas nonmotile (primary) cilia are required for sensory physiology and modulate various signal transduction pathways. Here we investigate the nonmotile ciliary signaling roles of parkin coregulated gene (PACRG), a protein linked to ciliary motility. PACRG is associated with the protofilament ribbon, a structure believed to dictate the regular arrangement of motility-associated ciliary components. Roles for protofilament ribbon–associated proteins in nonmotile cilia and cellular signaling have not been investigated. We show that PACRG localizes to a small subset of nonmotile cilia in Caenorhabditis elegans, suggesting an evolutionary adaptation for mediating specific sensory/signaling functions. We find that it influences a learning behavior known as gustatory plasticity, in which it is functionally coupled to heterotrimeric G-protein signaling. We also demonstrate that PACRG promotes longevity in C. elegans by acting upstream of the lifespan-promoting FOXO transcription factor DAF-16 and likely upstream of insulin/IGF signaling. Our findings establish previously unrecognized sensory/signaling functions for PACRG and point to a role for this protein in promoting longevity. Furthermore, our work suggests additional ciliary motility-signaling connections, since EFHC1 (EF-hand containing 1), a potential PACRG interaction partner similarly associated with the protofilament ribbon and ciliary motility, also positively regulates lifespan.
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Affiliation(s)
- Catrina M Loucks
- Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Nathan J Bialas
- Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | | | - Denise S Walker
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Laura J Grundy
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Chunmei Li
- Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - P Nick Inglis
- Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Katarzyna Kida
- School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - William R Schafer
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Oliver E Blacque
- School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Gert Jansen
- Department of Cell Biology, Erasmus MC, 3000 CA, Rotterdam, The Netherlands
| | - Michel R Leroux
- Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
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116
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Lee J, Chung YD. Ciliary subcompartments: how are they established and what are their functions? BMB Rep 2016; 48:380-7. [PMID: 25936781 PMCID: PMC4577287 DOI: 10.5483/bmbrep.2015.48.7.084] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Indexed: 12/15/2022] Open
Abstract
Cilia are conserved subcellular organelles with diverse sensory and developmental roles. Recently, they have emerged as crucial organelles whose dysfunction causes a wide spectrum of disorders called ciliopathies. Recent studies on the pathological mechanisms underlying ciliopathies showed that the ciliary compartment is further divided into subdomains with specific roles in the biogenesis, maintenance and function of cilia. Several conserved sets of molecules that play specific roles in each subcompartment have been discovered. Here we review recent progress on our understanding of ciliary subcompartments, especially focusing on the molecules required for their structure and/or function. [BMB Reports 2015; 48(7): 380-387]
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Affiliation(s)
- Jeongmi Lee
- Department of Life Science, University of Seoul, Seoul 130-743, Korea
| | - Yun Doo Chung
- Department of Life Science, University of Seoul, Seoul 130-743, Korea
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117
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Abstract
Genetic disorders, such as heterotaxy, first provided a link between cilia and developmental heart defects. Now, a genetic screen in mice shows that ciliary dysfunction may indeed be the major contributing factor in the etiology of congenital heart disease.
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Affiliation(s)
- Vijay Narasimhan
- Institute of Molecular and Cell Biology, Proteos, 61 Biopolis Drive, Singapore 138673
| | - Sudipto Roy
- Institute of Molecular and Cell Biology, Proteos, 61 Biopolis Drive, Singapore 138673; Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore; Department of Pediatrics, National University of Singapore, 1E Kent Ridge Drive, Singapore.
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118
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Yasunaga T, Hoff S, Schell C, Helmstädter M, Kretz O, Kuechlin S, Yakulov TA, Engel C, Müller B, Bensch R, Ronneberger O, Huber TB, Lienkamp SS, Walz G. The polarity protein Inturned links NPHP4 to Daam1 to control the subapical actin network in multiciliated cells. J Cell Biol 2016; 211:963-73. [PMID: 26644512 PMCID: PMC4674276 DOI: 10.1083/jcb.201502043] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Inturned-mediated complex formation of NPHP4 and DAAM1 is important for ciliogenesis and ciliary function in multiciliated cells, presumably because of its requirement for the local rearrangement of actin cytoskeleton. Motile cilia polarization requires intracellular anchorage to the cytoskeleton; however, the molecular machinery that supports this process remains elusive. We report that Inturned plays a central role in coordinating the interaction between cilia-associated proteins and actin-nucleation factors. We observed that knockdown of nphp4 in multiciliated cells of the Xenopus laevis epidermis compromised ciliogenesis and directional fluid flow. Depletion of nphp4 disrupted the subapical actin layer. Comparison to the structural defects caused by inturned depletion revealed striking similarities. Furthermore, coimmunoprecipitation assays demonstrated that the two proteins interact with each other and that Inturned mediates the formation of ternary protein complexes between NPHP4 and DAAM1. Knockdown of daam1, but not formin-2, resulted in similar disruption of the subapical actin web, whereas nphp4 depletion prevented the association of Inturned with the basal bodies. Thus, Inturned appears to function as an adaptor protein that couples cilia-associated molecules to actin-modifying proteins to rearrange the local actin cytoskeleton.
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Affiliation(s)
- Takayuki Yasunaga
- Renal Division, Department of Medicine, University of Freiburg Medical Center, 79106 Freiburg, Germany
| | - Sylvia Hoff
- Renal Division, Department of Medicine, University of Freiburg Medical Center, 79106 Freiburg, Germany
| | - Christoph Schell
- Renal Division, Department of Medicine, University of Freiburg Medical Center, 79106 Freiburg, Germany
| | - Martin Helmstädter
- Renal Division, Department of Medicine, University of Freiburg Medical Center, 79106 Freiburg, Germany
| | - Oliver Kretz
- Renal Division, Department of Medicine, University of Freiburg Medical Center, 79106 Freiburg, Germany Neuroanatomy, University of Freiburg, 79104 Freiburg, Germany
| | - Sebastian Kuechlin
- Renal Division, Department of Medicine, University of Freiburg Medical Center, 79106 Freiburg, Germany
| | - Toma A Yakulov
- Renal Division, Department of Medicine, University of Freiburg Medical Center, 79106 Freiburg, Germany
| | - Christina Engel
- Renal Division, Department of Medicine, University of Freiburg Medical Center, 79106 Freiburg, Germany
| | - Barbara Müller
- Renal Division, Department of Medicine, University of Freiburg Medical Center, 79106 Freiburg, Germany
| | - Robert Bensch
- Department of Computer Science, University of Freiburg, 79110 Freiburg, Germany Centre for Biological Signaling Studies, 79104 Freiburg, Germany
| | - Olaf Ronneberger
- Department of Computer Science, University of Freiburg, 79110 Freiburg, Germany Centre for Biological Signaling Studies, 79104 Freiburg, Germany
| | - Tobias B Huber
- Renal Division, Department of Medicine, University of Freiburg Medical Center, 79106 Freiburg, Germany Centre for Biological Signaling Studies, 79104 Freiburg, Germany
| | - Soeren S Lienkamp
- Renal Division, Department of Medicine, University of Freiburg Medical Center, 79106 Freiburg, Germany Centre for Biological Signaling Studies, 79104 Freiburg, Germany
| | - Gerd Walz
- Renal Division, Department of Medicine, University of Freiburg Medical Center, 79106 Freiburg, Germany Centre for Biological Signaling Studies, 79104 Freiburg, Germany
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119
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Kim JH, Ki SM, Joung JG, Scott E, Heynen-Genel S, Aza-Blanc P, Kwon CH, Kim J, Gleeson JG, Lee JE. Genome-wide screen identifies novel machineries required for both ciliogenesis and cell cycle arrest upon serum starvation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:1307-18. [PMID: 27033521 DOI: 10.1016/j.bbamcr.2016.03.021] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 03/19/2016] [Accepted: 03/22/2016] [Indexed: 01/01/2023]
Abstract
Biogenesis of the primary cilium, a cellular organelle mediating various signaling pathways, is generally coordinated with cell cycle exit/re-entry. Although the dynamic cell cycle-associated profile of the primary cilium has been largely accepted, the mechanism governing the link between ciliogenesis and cell cycle progression has been poorly understood. Using a human genome-wide RNAi screen, we identify genes encoding subunits of the spliceosome and proteasome as novel regulators of ciliogenesis. We demonstrate that 1) the mRNA processing-related hits are essential for RNA expression of molecules acting in cilia disassembly, such as AURKA and PLK1, and 2) the ubiquitin-proteasome systems (UPS)-involved hits are necessary for proteolysis of molecules acting in cilia assembly, such as IFT88 and CPAP. In particular, we show that these screen hit-associated mechanisms are crucial for both cilia assembly and cell cycle arrest in response to serum withdrawal. Finally, our data suggest that the mRNA processing mechanism may modulate the UPS-dependent decay of cilia assembly regulators to control ciliary resorption-coupled cell cycle re-entry.
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Affiliation(s)
- Ji Hyun Kim
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, #81 Irwon-Ro Gangnam-Gu, Seoul 06351, Republic of Korea
| | - Soo Mi Ki
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, #81 Irwon-Ro Gangnam-Gu, Seoul 06351, Republic of Korea
| | - Je-Gun Joung
- SGI, Samsung Medical Center, #81 Irwon-Ro Gangnam-Gu, Seoul 06351, Republic of Korea
| | - Eric Scott
- Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA
| | - Susanne Heynen-Genel
- High Content Screening and Functional Genomics Core, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | - Pedro Aza-Blanc
- High Content Screening and Functional Genomics Core, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | - Chang Hyuk Kwon
- SGI, Samsung Medical Center, #81 Irwon-Ro Gangnam-Gu, Seoul 06351, Republic of Korea
| | - Joon Kim
- GSMSE, KAIST, 291 Daehak-Ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Joseph G Gleeson
- Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA.
| | - Ji Eun Lee
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, #81 Irwon-Ro Gangnam-Gu, Seoul 06351, Republic of Korea; SGI, Samsung Medical Center, #81 Irwon-Ro Gangnam-Gu, Seoul 06351, Republic of Korea.
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120
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Borrego-Pinto J, Somogyi K, Karreman MA, König J, Müller-Reichert T, Bettencourt-Dias M, Gönczy P, Schwab Y, Lénárt P. Distinct mechanisms eliminate mother and daughter centrioles in meiosis of starfish oocytes. J Cell Biol 2016; 212:815-27. [PMID: 27002173 PMCID: PMC4810307 DOI: 10.1083/jcb.201510083] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 02/22/2016] [Indexed: 11/22/2022] Open
Abstract
Centriole elimination is an essential process that occurs in female meiosis of metazoa to reset centriole number in the zygote at fertilization. How centrioles are eliminated remains poorly understood. Here we visualize the entire elimination process live in starfish oocytes. Using specific fluorescent markers, we demonstrate that the two older, mother centrioles are selectively removed from the oocyte by extrusion into polar bodies. We show that this requires specific positioning of the second meiotic spindle, achieved by dynein-driven transport, and anchorage of the mother centriole to the plasma membrane via mother-specific appendages. In contrast, the single daughter centriole remaining in the egg is eliminated before the first embryonic cleavage. We demonstrate that these distinct elimination mechanisms are necessary because if mother centrioles are artificially retained, they cannot be inactivated, resulting in multipolar zygotic spindles. Thus, our findings reveal a dual mechanism to eliminate centrioles: mothers are physically removed, whereas daughters are eliminated in the cytoplasm, preparing the egg for fertilization.
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Affiliation(s)
- Joana Borrego-Pinto
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Kálmán Somogyi
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Matthia A Karreman
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Julia König
- Experimental Center, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
| | - Thomas Müller-Reichert
- Experimental Center, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany
| | | | - Pierre Gönczy
- Swiss Institute for Experimental Cancer Research, School of Life Sciences, Swiss Federal Institute of Technology, 1015 Lausanne, Switzerland
| | - Yannick Schwab
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Péter Lénárt
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
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121
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Li C, Jensen VL, Park K, Kennedy J, Garcia-Gonzalo FR, Romani M, De Mori R, Bruel AL, Gaillard D, Doray B, Lopez E, Rivière JB, Faivre L, Thauvin-Robinet C, Reiter JF, Blacque OE, Valente EM, Leroux MR. MKS5 and CEP290 Dependent Assembly Pathway of the Ciliary Transition Zone. PLoS Biol 2016; 14:e1002416. [PMID: 26982032 PMCID: PMC4794247 DOI: 10.1371/journal.pbio.1002416] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 02/24/2016] [Indexed: 11/19/2022] Open
Abstract
Cilia have a unique diffusion barrier (“gate”) within their proximal region, termed transition zone (TZ), that compartmentalises signalling proteins within the organelle. The TZ is known to harbour two functional modules/complexes (Meckel syndrome [MKS] and Nephronophthisis [NPHP]) defined by genetic interaction, interdependent protein localisation (hierarchy), and proteomic studies. However, the composition and molecular organisation of these modules and their links to human ciliary disease are not completely understood. Here, we reveal Caenorhabditis elegans CEP-290 (mammalian Cep290/Mks4/Nphp6 orthologue) as a central assembly factor that is specific for established MKS module components and depends on the coiled coil region of MKS-5 (Rpgrip1L/Rpgrip1) for TZ localisation. Consistent with a critical role in ciliary gate function, CEP-290 prevents inappropriate entry of membrane-associated proteins into cilia and keeps ARL-13 (Arl13b) from leaking out of cilia via the TZ. We identify a novel MKS module component, TMEM-218 (Tmem218), that requires CEP-290 and other MKS module components for TZ localisation and functions together with the NPHP module to facilitate ciliogenesis. We show that TZ localisation of TMEM-138 (Tmem138) and CDKL-1 (Cdkl1/Cdkl2/Cdkl3/Cdlk4 related), not previously linked to a specific TZ module, similarly depends on CEP-290; surprisingly, neither TMEM-138 or CDKL-1 exhibit interdependent localisation or genetic interactions with core MKS or NPHP module components, suggesting they are part of a distinct, CEP-290-associated module. Lastly, we show that families presenting with Oral-Facial-Digital syndrome type 6 (OFD6) have likely pathogenic mutations in CEP-290-dependent TZ proteins, namely Tmem17, Tmem138, and Tmem231. Notably, patient fibroblasts harbouring mutated Tmem17, a protein not yet ciliopathy-associated, display ciliogenesis defects. Together, our findings expand the repertoire of MKS module-associated proteins—including the previously uncharacterised mammalian Tmem80—and suggest an MKS-5 and CEP-290-dependent assembly pathway for building a functional TZ. The transition zone is a barrier structure required to maintain the dynamic composition and functional integrity of the cilium. This study describes the pathway by which the transition zone is assembled during cilium formation. The primary cilium is a structure found in most animal cell types. Much like an antenna, it is responsible for sensing extracellular signals, including light and small molecules, and conveying this information to the receiving cell and respective tissue or organ. At the base of the cilium is the transition zone (TZ), which acts as a “gate” to regulate the entry and exit of ciliary proteins required for signal transduction. Here, we use the nematode Caenorhabditis elegans as a model system to dissect how different proteins within the TZ assemble to form a functional barrier. We find that the TZ protein MKS-5 (Rpgrip1/Rpgrip1L orthologue) forms the foundation for two different assembly pathways involving two distinct modules: Nephronophthisis (NPHP) and Meckel syndrome (MKS). We show that at the base of the MKS module is CEP-290, another TZ protein that assembles MKS module proteins, including a novel TZ protein we identify as TMEM-218. CEP-290 also helps assemble a potentially separate submodule containing TMEM-138 and CDKL-1. Notably, we provide evidence that the MKS module protein TMEM-17 facilitates cilium formation and is disrupted in the human disorder (ciliopathy) Oral-Facial-Digital Syndrome type 6 (OFD6). Together, our findings provide essential insights into the assembly pathway of the ciliary TZ and suggest further connections between the transition zone and human health.
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Affiliation(s)
- Chunmei Li
- Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Victor L. Jensen
- Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Kwangjin Park
- Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Julie Kennedy
- School of Biomolecular & Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Francesc R. Garcia-Gonzalo
- Department of Biochemistry and Biophysics, Cardiovascular Research Institute, University of California, San Francisco, San Francisco, California, United States of America
| | - Marta Romani
- Neurogenetics Unit, Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
| | - Roberta De Mori
- Neurogenetics Unit, Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
| | - Ange-Line Bruel
- EA4271 GAD Génétique des Anomalies du Développement, FHU-TRANSLAD, Université Fédérale Bourgogne Franche-Comté, Dijon, France
| | | | - Bérénice Doray
- Service de Génétique clinique, CHRU Strasbourg, Strasbourg, France
| | - Estelle Lopez
- EA4271 GAD Génétique des Anomalies du Développement, FHU-TRANSLAD, Université Fédérale Bourgogne Franche-Comté, Dijon, France
| | - Jean-Baptiste Rivière
- EA4271 GAD Génétique des Anomalies du Développement, FHU-TRANSLAD, Université Fédérale Bourgogne Franche-Comté, Dijon, France
- Laboratoire de Génétique moléculaire, Plateau Technique de Biologie, CHU Dijon, Dijon, France
| | - Laurence Faivre
- EA4271 GAD Génétique des Anomalies du Développement, FHU-TRANSLAD, Université Fédérale Bourgogne Franche-Comté, Dijon, France
- Centre de Génétique, FHU-TRANSLAD, Hôpital d’Enfants, CHU Dijon, Dijon, France
| | - Christel Thauvin-Robinet
- EA4271 GAD Génétique des Anomalies du Développement, FHU-TRANSLAD, Université Fédérale Bourgogne Franche-Comté, Dijon, France
- Centre de Génétique, FHU-TRANSLAD, Hôpital d’Enfants, CHU Dijon, Dijon, France
| | - Jeremy F. Reiter
- Department of Biochemistry and Biophysics, Cardiovascular Research Institute, University of California, San Francisco, San Francisco, California, United States of America
| | - Oliver E. Blacque
- School of Biomolecular & Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Enza Maria Valente
- Neurogenetics Unit, Mendel Laboratory, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
- Department of Medicine and Surgery, University of Salerno, Salerno, Italy
| | - Michel R. Leroux
- Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
- * E-mail:
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Promponas VJ, Katsani KR, Blencowe BJ, Ouzounis CA. Sequence evidence for common ancestry of eukaryotic endomembrane coatomers. Sci Rep 2016; 6:22311. [PMID: 26931514 PMCID: PMC4773986 DOI: 10.1038/srep22311] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 02/12/2016] [Indexed: 12/27/2022] Open
Abstract
Eukaryotic cells are defined by compartments through which the trafficking of macromolecules is mediated by large complexes, such as the nuclear pore, transport vesicles and intraflagellar transport. The assembly and maintenance of these complexes is facilitated by endomembrane coatomers, long suspected to be divergently related on the basis of structural and more recently phylogenomic analysis. By performing supervised walks in sequence space across coatomer superfamilies, we uncover subtle sequence patterns that have remained elusive to date, ultimately unifying eukaryotic coatomers by divergent evolution. The conserved residues shared by 3,502 endomembrane coatomer components are mapped onto the solenoid superhelix of nucleoporin and COPII protein structures, thus determining the invariant elements of coatomer architecture. This ancient structural motif can be considered as a universal signature connecting eukaryotic coatomers involved in multiple cellular processes across cell physiology and human disease.
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Affiliation(s)
- Vasilis J. Promponas
- Bioinformatics Research Laboratory, Department of Biological Sciences, New Campus, University of Cyprus, PO Box 20537, CY-1678 Nicosia, Cyprus
| | - Katerina R. Katsani
- Department of Molecular Biology & Genetics, Democritus University of Thrace, GR-68100 Alexandroupolis, Greece
| | - Benjamin J. Blencowe
- Donnelly Centre for Cellular & Biomolecular Research, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
| | - Christos A. Ouzounis
- Bioinformatics Research Laboratory, Department of Biological Sciences, New Campus, University of Cyprus, PO Box 20537, CY-1678 Nicosia, Cyprus
- Donnelly Centre for Cellular & Biomolecular Research, University of Toronto, 160 College Street, Toronto, Ontario M5S 3E1, Canada
- Biological Computation & Process Laboratory (BCPL), Chemical Process Research Institute (CPERI), Centre for Research & Technology (CERTH), PO Box 361, GR-57001 Thessalonica, Greece
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Hilgendorf KI, Johnson CT, Jackson PK. The primary cilium as a cellular receiver: organizing ciliary GPCR signaling. Curr Opin Cell Biol 2016; 39:84-92. [PMID: 26926036 DOI: 10.1016/j.ceb.2016.02.008] [Citation(s) in RCA: 160] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Revised: 02/03/2016] [Accepted: 02/04/2016] [Indexed: 12/12/2022]
Abstract
The primary cilium is an antenna-like cellular protrusion mediating sensory and neuroendocrine signaling. Its localization within tissue architecture and a growing list of cilia-localized receptors, in particular G-protein-coupled receptors, determine a host of crucial physiologies, which are disrupted in human ciliopathies. Here, we discuss recent advances in the identification and characterization of ciliary signaling components and pathways. Recent studies have highlighted the unique signaling environment of the primary cilium and we are just beginning to understand how this design allows for highly amplified and regulated signaling.
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Affiliation(s)
- Keren I Hilgendorf
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Carl T Johnson
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Medicine, Stem Cell and Regenerative Medicine PhD Program, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Peter K Jackson
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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A paneukaryotic genomic analysis of the small GTPase RABL2 underscores the significance of recurrent gene loss in eukaryote evolution. Biol Direct 2016; 11:5. [PMID: 26832778 PMCID: PMC4736243 DOI: 10.1186/s13062-016-0107-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 01/27/2016] [Indexed: 12/30/2022] Open
Abstract
Background The cilium (flagellum) is a complex cellular structure inherited from the last eukaryotic common ancestor (LECA). A large number of ciliary proteins have been characterized in a few model organisms, but their evolutionary history often remains unexplored. One such protein is the small GTPase RABL2, recently implicated in the assembly of the sperm tail in mammals. Results Using the wealth of currently available genome and transcriptome sequences, including data from our on-going sequencing projects, we systematically analyzed the phylogenetic distribution and evolutionary history of RABL2 orthologs. Our dense taxonomic sampling revealed the presence of RABL2 genes in nearly all major eukaryotic lineages, including small “obscure” taxa such as breviates, ancyromonads, malawimonads, jakobids, picozoans, or palpitomonads. The phyletic pattern of RABL2 genes indicates that it was present already in the LECA. However, some organisms lack RABL2 as a result of secondary loss and our present sampling predicts well over 30 such independent events during the eukaryote evolution. The distribution of RABL2 genes correlates with the presence/absence of cilia: not a single well-established cilium-lacking species has retained a RABL2 ortholog. However, several ciliated taxa, most notably nematodes, some arthropods and platyhelminths, diplomonads, and ciliated subgroups of apicomplexans and embryophytes, lack RABL2 as well, suggesting some simplification in their cilium-associated functions. On the other hand, several algae currently unknown to form cilia, e.g., the “prasinophytes” of the genus Prasinoderma or the ochrophytes Pelagococcus subviridis and Pinguiococcus pyrenoidosus, turned out to encode not only RABL2, but also homologs of some hallmark ciliary proteins, suggesting the existence of a cryptic flagellated stage in their life cycles. We additionally obtained insights into the evolution of the RABL2 gene architecture, which seems to have ancestrally consisted of eight exons subsequently modified not only by lineage-specific intron loss and gain, but also by recurrent loss of the terminal exon encoding a poorly conserved C-terminal extension. Conclusions Our comparative analysis supports the notion that RABL2 is an ancestral component of the eukaryotic cilium and underscores the still underappreciated magnitude of recurrent gene loss, or reductive evolution in general, in the history of eukaryotic genomes and cells. Reviewers This article was reviewed by Berend Snel and James O. McInerney. Electronic supplementary material The online version of this article (doi:10.1186/s13062-016-0107-8) contains supplementary material, which is available to authorized users.
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125
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Cellular Mechanisms of Ciliary Length Control. Cells 2016; 5:cells5010006. [PMID: 26840332 PMCID: PMC4810091 DOI: 10.3390/cells5010006] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 01/21/2016] [Accepted: 01/25/2016] [Indexed: 12/12/2022] Open
Abstract
Cilia and flagella are evolutionarily conserved, membrane-bound, microtubule-based organelles on the surface of most eukaryotic cells. They play important roles in coordinating a variety of signaling pathways during growth, development, cell mobility, and tissue homeostasis. Defects in ciliary structure or function are associated with multiple human disorders called ciliopathies. These diseases affect diverse tissues, including, but not limited to the eyes, kidneys, brain, and lungs. Many processes must be coordinated simultaneously in order to initiate ciliogenesis. These include cell cycle, vesicular trafficking, and axonemal extension. Centrioles play a central role in both cell cycle progression and ciliogenesis, making the transition between basal bodies and mitotic spindle organizers integral to both processes. The maturation of centrioles involves a functional shift from cell division toward cilium nucleation which takes place concurrently with its migration and fusion to the plasma membrane. Several proteinaceous structures of the distal appendages in mother centrioles are required for this docking process. Ciliary assembly and maintenance requires a precise balance between two indispensable processes; so called assembly and disassembly. The interplay between them determines the length of the resulting cilia. These processes require a highly conserved transport system to provide the necessary substances at the tips of the cilia and to recycle ciliary turnover products to the base using a based microtubule intraflagellar transport (IFT) system. In this review; we discuss the stages of ciliogenesis as well as mechanisms controlling the lengths of assembled cilia.
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Sugiyama Y, Shelley EJ, Yoder BK, Kozmik Z, May-Simera HL, Beales PL, Lovicu FJ, McAvoy JW. Non-essential role for cilia in coordinating precise alignment of lens fibres. Mech Dev 2016; 139:10-7. [PMID: 26825015 DOI: 10.1016/j.mod.2016.01.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 01/21/2016] [Accepted: 01/24/2016] [Indexed: 12/14/2022]
Abstract
The primary cilium, a microtubule-based organelle found in most cells, is a centre for mechano-sensing fluid movement and cellular signalling, notably through the Hedgehog pathway. We recently found that each lens fibre cell has an apically situated primary cilium that is polarised to the side of the cell facing the anterior pole of the lens. The direction of polarity is similar in neighbouring cells so that in the global view, lens fibres exhibit planar cell polarity (PCP) along the equatorial-anterior polar axis. Ciliogenesis has been associated with the establishment of PCP, although the exact relationship between PCP and the role of cilia is still controversial. To test the hypothesis that the primary cilia have a role in coordinating the precise alignment/orientation of the fibre cells, IFT88, a key component of the intraflagellar transport (IFT) complex, was removed specifically from the lens at different developmental stages using several lens-specific Cre-expressing mouse lines (MLR10- and LR-Cre). Irrespective of which Cre-line was adopted, both demonstrated that in IFT88-depleted cells, the ciliary axoneme was absent or substantially shortened, confirming the disruption of primary cilia formation. However no obvious histological defects were detected even when IFT88 was removed from the lens placode as early as E9.5. Specifically, the lens fibres aligned/oriented towards the poles to form the characteristic Y-shaped sutures as normal. Consistent with this, in primary lens epithelial explants prepared from these conditional knockout mouse lenses, the basal bodies still showed polarised localisation at the apical surface of elongating cells upon FGF-induced fibre differentiation. We further investigated the lens phenotype in knockouts of Bardet-Biedl Syndrome (BBS) proteins 4 and 8, the components of the BBSome complex which modulate ciliary function. In these BBS4 and 8 knockout lenses, again we found the pattern of the anterior sutures formed by the apical tips of elongating/migrating fibres were comparable to the control lenses. Taken together, these results indicate that primary cilia do not play an essential role in the precise cellular alignment/orientation of fibre cells. Thus, it appears that in the lens cilia are not required to establish PCP.
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Affiliation(s)
- Yuki Sugiyama
- Save Sight Institute, The University of Sydney, Sydney, NSW 2000, Australia.
| | | | - Bradley K Yoder
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Zbynek Kozmik
- Department of Transcriptional Regulation, Institute of Molecular Genetics, Prague CZ-14220, Czech Republic
| | - Helen L May-Simera
- Institute of Zoology, Johannes-Gutenberg University, Mainz 55128, Germany
| | - Philip L Beales
- Genetics and Genomic Medicine, University College London Institute of Child Health, London WC1N 1EH, UK
| | - Frank J Lovicu
- Anatomy and Histology, School of Medical Sciences and Bosch Institute, University of Sydney, Sydney, NSW 2006, Australia
| | - John W McAvoy
- Save Sight Institute, The University of Sydney, Sydney, NSW 2000, Australia
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127
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Takao D, Verhey KJ. Gated entry into the ciliary compartment. Cell Mol Life Sci 2016; 73:119-27. [PMID: 26472341 PMCID: PMC4959937 DOI: 10.1007/s00018-015-2058-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 09/28/2015] [Accepted: 09/29/2015] [Indexed: 11/26/2022]
Abstract
Cilia and flagella play important roles in cell motility and cell signaling. These functions require that the cilium establishes and maintains a unique lipid and protein composition. Recent work indicates that a specialized region at the base of the cilium, the transition zone, serves as both a barrier to entry and a gate for passage of select components. For at least some cytosolic proteins, the barrier and gate functions are provided by a ciliary pore complex (CPC) that shares molecular and mechanistic properties with nuclear gating. Specifically, nucleoporins of the CPC limit the diffusional entry of cytosolic proteins in a size-dependent manner and enable the active transport of large molecules and complexes via targeting signals, importins, and the small G protein Ran. For membrane proteins, the septin protein SEPT2 is part of the barrier to entry whereas the gating function is carried out and/or regulated by proteins associated with ciliary diseases (ciliopathies) such as nephronophthisis, Meckel–Gruber syndrome and Joubert syndrome. Here, we discuss the evidence behind these models of ciliary gating as well as the similarities to and differences from nuclear gating.
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Affiliation(s)
- Daisuke Takao
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Pl, Ann Arbor, MI 48109 USA
| | - Kristen J. Verhey
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Pl, Ann Arbor, MI 48109 USA
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Izawa I, Goto H, Kasahara K, Inagaki M. Current topics of functional links between primary cilia and cell cycle. Cilia 2015; 4:12. [PMID: 26719793 PMCID: PMC4696186 DOI: 10.1186/s13630-015-0021-1] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 12/10/2015] [Indexed: 12/31/2022] Open
Abstract
Primary cilia, microtubule-based sensory structures, orchestrate various critical signals during development and tissue homeostasis. In view of the rising interest into the reciprocal link between ciliogenesis and cell cycle, we discuss here several recent advances to understand the molecular link between the individual step of ciliogenesis and cell cycle control. At the onset of ciliogenesis (the transition from centrosome to basal body), distal appendage proteins have been established as components indispensable for the docking of vesicles at the mother centriole. In the initial step of axonemal extension, CP110, Ofd1, and trichoplein, key negative regulators of ciliogenesis, are found to be removed by a kinase-dependent mechanism, autophagy, and ubiquitin–proteasome system, respectively. Of note, their disposal functions as a restriction point to decide that the axonemal nucleation and extension begin. In the elongation step, Nde1, a negative regulator of ciliary length, is revealed to be ubiquitylated and degraded by CDK5-SCFFbw7 in a cell cycle-dependent manner. With regard to ciliary length control, it has been uncovered in flagellar shortening of Chlamydomonas that cilia itself transmit a ciliary length signal to cytoplasm. At the ciliary resorption step upon cell cycle re-entry, cilia are found to be disassembled not only by Aurora A-HDAC6 pathway but also by Nek2-Kif24 and Plk1-Kif2A pathways through their microtubule-depolymerizing activity. On the other hand, it is becoming evident that the presence of primary cilia itself functions as a structural checkpoint for cell cycle re-entry. These data suggest that ciliogenesis and cell cycle intimately link each other, and further elucidation of these mechanisms will contribute to understanding the pathology of cilia-related disease including cancer and discovering targets of therapeutic interventions.
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Affiliation(s)
- Ichiro Izawa
- Division of Biochemistry, Aichi Cancer Center Research Institute, 1-1 Kanokoden, Chikusa-ku, Nagoya, 464-8681 Japan
| | - Hidemasa Goto
- Division of Biochemistry, Aichi Cancer Center Research Institute, 1-1 Kanokoden, Chikusa-ku, Nagoya, 464-8681 Japan ; Department of Cellular Oncology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550 Japan
| | - Kousuke Kasahara
- Division of Biochemistry, Aichi Cancer Center Research Institute, 1-1 Kanokoden, Chikusa-ku, Nagoya, 464-8681 Japan ; Department of Oncology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Aichi 467-8603 Japan
| | - Masaki Inagaki
- Division of Biochemistry, Aichi Cancer Center Research Institute, 1-1 Kanokoden, Chikusa-ku, Nagoya, 464-8681 Japan ; Department of Cellular Oncology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550 Japan
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Plattner H. Signalling in ciliates: long- and short-range signals and molecular determinants for cellular dynamics. Biol Rev Camb Philos Soc 2015; 92:60-107. [PMID: 26487631 DOI: 10.1111/brv.12218] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 07/28/2015] [Accepted: 08/21/2015] [Indexed: 12/30/2022]
Abstract
In ciliates, unicellular representatives of the bikont branch of evolution, inter- and intracellular signalling pathways have been analysed mainly in Paramecium tetraurelia, Paramecium multimicronucleatum and Tetrahymena thermophila and in part also in Euplotes raikovi. Electrophysiology of ciliary activity in Paramecium spp. is a most successful example. Established signalling mechanisms include plasmalemmal ion channels, recently established intracellular Ca2+ -release channels, as well as signalling by cyclic nucleotides and Ca2+ . Ca2+ -binding proteins (calmodulin, centrin) and Ca2+ -activated enzymes (kinases, phosphatases) are involved. Many organelles are endowed with specific molecules cooperating in signalling for intracellular transport and targeted delivery. Among them are recently specified soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs), monomeric GTPases, H+ -ATPase/pump, actin, etc. Little specification is available for some key signal transducers including mechanosensitive Ca2+ -channels, exocyst complexes and Ca2+ -sensor proteins for vesicle-vesicle/membrane interactions. The existence of heterotrimeric G-proteins and of G-protein-coupled receptors is still under considerable debate. Serine/threonine kinases dominate by far over tyrosine kinases (some predicted by phosphoproteomic analyses). Besides short-range signalling, long-range signalling also exists, e.g. as firmly installed microtubular transport rails within epigenetically determined patterns, thus facilitating targeted vesicle delivery. By envisaging widely different phenomena of signalling and subcellular dynamics, it will be shown (i) that important pathways of signalling and cellular dynamics are established already in ciliates, (ii) that some mechanisms diverge from higher eukaryotes and (iii) that considerable uncertainties still exist about some essential aspects of signalling.
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Affiliation(s)
- Helmut Plattner
- Department of Biology, University of Konstanz, PO Box M625, 78457, Konstanz, Germany
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130
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Kawasaki M, Ezura Y, Hayata T, Notomi T, Izu Y, Noda M. TGF-β Suppresses Ift88 Expression in Chondrocytic ATDC5 Cells. J Cell Physiol 2015; 230:2788-95. [PMID: 25828538 DOI: 10.1002/jcp.25005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 03/27/2015] [Indexed: 01/08/2023]
Abstract
Ift88 is an intraflagella transport protein, critical for the cilium, and has been shown to be required for the maintenance of chondrocytes and cartilage. However, how Ift88 is controlled by cytokines that play a role in osteoarthritis is not well understood. Therefore, we examined the effects of TGF-β on the expression of Ift88. We used ATDC5 cells as chondrocytes and analyzed the effects of TGF-β on gene expression. TGF-β treatment suppresses the levels of Ift88 mRNA in a dose-dependent manner starting from as low as 0.5 ng/mL and reaching the nadir at around 2 ng/mL. TGF-β treatment also suppresses the protein levels of Ift88. TGF-β suppression of Ift88 is still observed when the cells are cultured in the presence of a transcriptional inhibitor while the TGF-β suppression is weakened in the presence of a protein synthesis inhibitor, cycloheximide. TGF-β treatment suppresses the levels of Ift88 mRNA stability suggesting the presence of posttranscriptional regulation. TGF-β treatment reduces the number of cilia positive cells and suppresses average length of cilia. Knockdown of Ift88 by siRNA enhances TGF-β-induced increase in type II collagen mRNA expression in ATDC5 cells revealing the suppressive role of Ift88 on TGF-β-induced regulation of extracellular matrix protein expression. TGF-β also suppresses Ift88 mRNA expression in primary culture of rib chondrocytes. These data indicate that TGF-β regulates Ift88 gene expression at least in part via posttrascriptional manner.
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Affiliation(s)
- Makiri Kawasaki
- Department of Molecular Pharmacology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | - Yoichi Ezura
- Department of Molecular Pharmacology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | - Tadayoshi Hayata
- Department of Molecular Pharmacology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | - Takuya Notomi
- Department of Molecular Pharmacology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | - Yayoi Izu
- Department of Molecular Pharmacology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | - Masaki Noda
- Department of Molecular Pharmacology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
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Kong JN, Hardin K, Dinkins M, Wang G, He Q, Mujadzic T, Zhu G, Bielawski J, Spassieva S, Bieberich E. Regulation of Chlamydomonas flagella and ependymal cell motile cilia by ceramide-mediated translocation of GSK3. Mol Biol Cell 2015; 26:4451-65. [PMID: 26446842 PMCID: PMC4666139 DOI: 10.1091/mbc.e15-06-0371] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 09/30/2015] [Indexed: 12/23/2022] Open
Abstract
Cilia are important organelles formed by cell membrane protrusions; however, little is known about their regulation by membrane lipids. A novel, evolutionarily conserved activation mechanism for GSK3 by the sphingolipid (phyto)ceramide is characterized that is critical for ciliogenesis in Chlamydomonas and murine ependymal cells. Cilia are important organelles formed by cell membrane protrusions; however, little is known about their regulation by membrane lipids. We characterize a novel activation mechanism for glycogen synthase kinase-3 (GSK3) by the sphingolipids phytoceramide and ceramide that is critical for ciliogenesis in Chlamydomonas and murine ependymal cells, respectively. We show for the first time that Chlamydomonas expresses serine palmitoyl transferase (SPT), the first enzyme in (phyto)ceramide biosynthesis. Inhibition of SPT in Chlamydomonas by myriocin led to loss of flagella and reduced tubulin acetylation, which was prevented by supplementation with the precursor dihydrosphingosine. Immunocytochemistry showed that (phyto)ceramide was colocalized with phospho–Tyr-216-GSK3 (pYGSK3) at the base and tip of Chlamydomonas flagella and motile cilia in ependymal cells. The (phyto)ceramide distribution was consistent with that of a bifunctional ceramide analogue UV cross-linked and visualized by click-chemistry–mediated fluorescent labeling. Ceramide depletion, by myriocin or neutral sphingomyelinase deficiency (fro/fro mouse), led to GSK3 dephosphorylation and defective flagella and cilia. Motile cilia were rescued and pYGSK3 localization restored by incubation of fro/fro ependymal cells with exogenous C24:1 ceramide, which directly bound to pYGSK3. Our findings suggest that (phyto)ceramide-mediated translocation of pYGSK into flagella and cilia is an evolutionarily conserved mechanism fundamental to the regulation of ciliogenesis.
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Affiliation(s)
- Ji Na Kong
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912
| | - Kara Hardin
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912
| | - Michael Dinkins
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912
| | - Guanghu Wang
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912
| | - Qian He
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912
| | - Tarik Mujadzic
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912
| | - Gu Zhu
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912
| | - Jacek Bielawski
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425
| | - Stefka Spassieva
- Department of Medicine, Medical University of South Carolina, Charleston, SC 29425
| | - Erhard Bieberich
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Georgia Regents University, Augusta, GA 30912
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132
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Szumska J, Qatato M, Rehders M, Führer D, Biebermann H, Grandy DK, Köhrle J, Brix K. Trace Amine-Associated Receptor 1 Localization at the Apical Plasma Membrane Domain of Fisher Rat Thyroid Epithelial Cells Is Confined to Cilia. Eur Thyroid J 2015; 4:30-41. [PMID: 26601071 PMCID: PMC4640295 DOI: 10.1159/000434717] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 06/02/2015] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND The trace amine-associated receptor 1 (Taar1) is one member of the Taar family of G-protein-coupled receptors (GPCR) accepting various biogenic amines as ligands. It has been proposed that Taar1 mediates rapid, membrane-initiated effects of thyronamines, the endogenous decarboxylated and deiodinated relatives of the classical thyroid hormones T4 and T3. OBJECTIVES Although the physiological actions of thyronamines in general and 3-iodothyronamine (T1AM) in particular are incompletely understood, studies published to date suggest that synthetic T1AM-activated Taar1 signaling antagonizes thyromimetic effects exerted by T3. However, the location of Taar1 is currently unknown. METHODS To fill this gap in our knowledge we employed immunofluorescence microscopy and a polyclonal antibody to detect Taar1 protein expression in thyroid tissue from Fisher rats, wild-type and taar1-deficient mice, and in the polarized FRT cells. RESULTS With this approach we found that Taar1 is expressed in the membranes of subcellular compartments of the secretory pathway and on the apical plasma membrane of FRT cells. Three-dimensional analyses further revealed Taar1 immunoreactivity in cilial extensions of postconfluent FRT cell cultures that had formed follicle-like structures. CONCLUSIONS The results suggest Taar1 transport along the secretory pathway and its accumulation in the primary cilium of thyrocytes. These findings are of significance considering the increasing interest in the role of cilia in harboring functional GPCR. We hypothesize that thyronamines can reach and activate Taar1 in thyroid follicular epithelia by acting from within the thyroid follicle lumen, their potential site of synthesis, as part of a nonclassical mechanism of thyroid autoregulation.
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Affiliation(s)
- Joanna Szumska
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Maria Qatato
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Maren Rehders
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Dagmar Führer
- Department of Endocrinology and Metabolism and Division of Laboratory Research, University of Duisburg-Essen, Essen, Germany
| | - Heike Biebermann
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - David K. Grandy
- Department of Physiology and Pharmacology, School of Medicine and the Knight Cardiovascular Institute, Oregon Health & Science University, Portland, Oreg., USA
| | - Josef Köhrle
- Institut für Experimentelle Endokrinologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Klaudia Brix
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
- *Dr. Klaudia Brix, Department of Life Sciences and Chemistry, Jacobs University Bremen, Campus Ring 1, DE-28759 Bremen (Germany), E-Mail
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133
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Dean AB, Mitchell DR. Late steps in cytoplasmic maturation of assembly-competent axonemal outer arm dynein in Chlamydomonas require interaction of ODA5 and ODA10 in a complex. Mol Biol Cell 2015; 26:3596-605. [PMID: 26310446 PMCID: PMC4603930 DOI: 10.1091/mbc.e15-05-0317] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 08/18/2015] [Indexed: 11/14/2022] Open
Abstract
In humans, homologues of Chlamydomonas ciliary docking complex subunit DC2 and assembly factor ODA10 are interacting axonemal proteins needed for outer dynein arm assembly. Surprisingly, Chlamydomonas ODA10 does not interact with DC2, localizes to a proximal axonemal domain, and is needed for cytoplasmic steps in dynein assembly, not for docking. Axonemal dyneins are multisubunit enzymes that must be preassembled in the cytoplasm, transported into cilia by intraflagellar transport, and bound to specific sites on doublet microtubules, where their activity facilitates microtubule sliding-based motility. Outer dynein arms (ODAs) require assembly factors to assist their preassembly, transport, and attachment to cargo (specific doublet A-tubule sites). In Chlamydomonas, three assembly factors—ODA5, ODA8, and ODA10—show genetic interactions and have been proposed to interact in a complex, but we recently showed that flagellar ODA8 does not copurify with ODA5 or ODA10. Here we show that ODA5 and ODA10 depend on each other for stability and coexist in a complex in both cytoplasmic and flagellar extracts. Immunofluorescence and immuno–electron microscopy reveal that ODA10 in flagella localizes strictly to a proximal region of doublet number 1, which completely lacks ODAs in Chlamydomonas. Studies of the in vitro binding of ODAs to axonemal doublets reveal a role for the ODA5/ODA10 assembly complex in cytoplasmic maturation of ODAs into a form that can bind to doublet microtubules.
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Affiliation(s)
- Anudariya B Dean
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, NY 13210
| | - David R Mitchell
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, NY 13210
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134
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Schou KB, Pedersen LB, Christensen ST. Ins and outs of GPCR signaling in primary cilia. EMBO Rep 2015; 16:1099-113. [PMID: 26297609 DOI: 10.15252/embr.201540530] [Citation(s) in RCA: 145] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 07/01/2015] [Indexed: 12/17/2022] Open
Abstract
Primary cilia are specialized microtubule-based signaling organelles that convey extracellular signals into a cellular response in most vertebrate cell types. The physiological significance of primary cilia is underscored by the fact that defects in assembly or function of these organelles lead to a range of severe diseases and developmental disorders. In most cell types of the human body, signaling by primary cilia involves different G protein-coupled receptors (GPCRs), which transmit specific signals to the cell through G proteins to regulate diverse cellular and physiological events. Here, we provide an overview of GPCR signaling in primary cilia, with main focus on the rhodopsin-like (class A) and the smoothened/frizzled (class F) GPCRs. We describe how such receptors dynamically traffic into and out of the ciliary compartment and how they interact with other classes of ciliary GPCRs, such as class B receptors, to control ciliary function and various physiological and behavioral processes. Finally, we discuss future avenues for developing GPCR-targeted drug strategies for the treatment of ciliopathies.
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135
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Lu X, Sipe CW. Developmental regulation of planar cell polarity and hair-bundle morphogenesis in auditory hair cells: lessons from human and mouse genetics. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2015; 5:85-101. [PMID: 26265594 DOI: 10.1002/wdev.202] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 06/12/2015] [Accepted: 06/29/2015] [Indexed: 12/11/2022]
Abstract
Hearing loss is the most common and costly sensory defect in humans and genetic causes underlie a significant proportion of affected individuals. In mammals, sound is detected by hair cells (HCs) housed in the cochlea of the inner ear, whose function depends on a highly specialized mechanotransduction organelle, the hair bundle. Understanding the factors that regulate the development and functional maturation of the hair bundle is crucial for understanding the pathophysiology of human deafness. Genetic analysis of deafness genes in animal models, together with complementary forward genetic screens and conditional knock-out mutations in essential genes, have provided great insights into the molecular machinery underpinning hair-bundle development and function. In this review, we highlight recent advances in our understanding of hair-bundle morphogenesis, with an emphasis on the molecular pathways governing hair-bundle polarity and orientation. We next discuss the proteins and structural elements important for hair-cell mechanotransduction as well as hair-bundle cohesion and maintenance. In addition, developmental signals thought to regulate tonotopic features of HCs are introduced. Finally, novel approaches that complement classic genetics for studying the molecular etiology of human deafness are presented. WIREs Dev Biol 2016, 5:85-101. doi: 10.1002/wdev.202 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Xiaowei Lu
- Department of Cell Biology, University of Virginia, Charlottesville, VA, USA
| | - Conor W Sipe
- Department of Biology, University of Virginia, Charlottesville, VA, USA
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136
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Structure of Rab11-FIP3-Rabin8 reveals simultaneous binding of FIP3 and Rabin8 effectors to Rab11. Nat Struct Mol Biol 2015; 22:695-702. [PMID: 26258637 DOI: 10.1038/nsmb.3065] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 07/07/2015] [Indexed: 12/20/2022]
Abstract
The small GTPase Rab11 and its effectors FIP3 and Rabin8 are essential to membrane-trafficking pathways required for cytokinesis and ciliogenesis. Although effector binding is generally assumed to be sequential and mutually exclusive, we show that Rab11 can simultaneously bind FIP3 and Rabin8. We determined crystal structures of human Rab11-GMPPNP-Rabin8 and Rab11-GMPPNP-FIP3-Rabin8. The structures reveal that the C-terminal domain of Rabin8 adopts a previously undescribed fold that interacts with Rab11 at an unusual effector-binding site neighboring the canonical FIP3-binding site. We show that Rab11-GMPPNP-FIP3-Rabin8 is more stable than Rab11-GMPPNP-Rabin8, owing to direct interaction between Rabin8 and FIP3 within the dual effector-bound complex. The data allow us to propose a model for how membrane-targeting complexes assemble at the trans-Golgi network and recycling endosomes, through multiple weak interactions that create high-avidity complexes.
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137
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Maskey D, Marlin MC, Kim S, Kim S, Ong EC, Li G, Tsiokas L. Cell cycle-dependent ubiquitylation and destruction of NDE1 by CDK5-FBW7 regulates ciliary length. EMBO J 2015. [PMID: 26206584 DOI: 10.15252/embj.201490831] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Primary cilia start forming within the G1 phase of the cell cycle and continue to grow as cells exit the cell cycle (G0). They start resorbing when cells re-enter the cell cycle (S phase) and are practically invisible in mitosis. The mechanisms by which cilium biogenesis and disassembly are coupled to the cell cycle are complex and not well understood. We previously identified the centrosomal phosphoprotein NDE1 as a negative regulator of ciliary length and showed that its levels inversely correlate with ciliogenesis. Here, we identify the tumor suppressor FBW7 (also known as FBXW7, CDC4, AGO, or SEL-10) as the E3 ligase that mediates the destruction of NDE1 upon entry into G1. CDK5, a kinase active in G1/G0, primes NDE1 for FBW7-mediated recognition. Cells depleted of FBW7 or CDK5 show enhanced levels of NDE1 and a reduction in ciliary length, which is corrected in cells depleted of both FBW7 or CDK5 and NDE1. These data show that cell cycle-dependent mechanisms can control ciliary length through a CDK5-FBW7-NDE1 pathway.
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Affiliation(s)
- Dipak Maskey
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Matthew Caleb Marlin
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Seokho Kim
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Sehyun Kim
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - E-Ching Ong
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Guangpu Li
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Leonidas Tsiokas
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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138
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Abstract
It is 20 years since the identification of PKD1, the major gene mutated in autosomal dominant polycystic kidney disease (ADPKD), followed closely by the cloning of PKD2. These major breakthroughs have led in turn to a period of intense investigation into the function of the two proteins encoded, polycystin-1 and polycystin-2, and how defects in either protein lead to cyst formation and nonrenal phenotypes. In this review, we summarize the major findings in this area and present a current model of how the polycystin proteins function in health and disease.
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139
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Desvignes T, Nguyen T, Chesnel F, Bouleau A, Fauvel C, Bobe J. X-Linked Retinitis Pigmentosa 2 Is a Novel Maternal-Effect Gene Required for Left-Right Asymmetry in Zebrafish. Biol Reprod 2015; 93:42. [PMID: 26134862 DOI: 10.1095/biolreprod.115.130575] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Accepted: 06/10/2015] [Indexed: 01/05/2023] Open
Abstract
Retinitis pigmentosa 2 (RP2) gene is responsible for up to 20% of X-linked retinitis pigmentosa, a severe heterogeneous genetic disorder resulting in progressive retinal degeneration in humans. In vertebrates, several bodies of evidence have clearly established the role of Rp2 protein in cilia genesis and/or function. Unexpectedly, some observations in zebrafish have suggested the oocyte-predominant expression of the rp2 gene, a typical feature of maternal-effect genes. In the present study, we investigate the maternal inheritance of rp2 gene products in zebrafish eggs in order to address whether rp2 could be a novel maternal-effect gene required for normal development. Although both rp2 mRNA and corresponding protein are expressed during oogenesis, rp2 mRNA is maternally inherited, in contrast to Rp2 protein. A knockdown of the protein transcribed from both rp2 maternal and zygotic mRNA results in delayed epiboly and severe developmental defects, including eye malformations, that were not observed when only the protein from zygotic origin was knocked down. Moreover, the knockdown of maternal and zygotic Rp2 revealed a high incidence of left-right asymmetry establishment defects compared to only zygotic knockdown. Here we show that rp2 is a novel maternal-effect gene exclusively expressed in oocytes within the zebrafish ovary and demonstrate that maternal rp2 mRNA is essential for successful embryonic development and thus contributes to egg developmental competence. Our observations also reveal that Rp2 protein translated from maternal mRNA is important to allow normal heart loop formation, thus providing evidence of a direct maternal contribution to left-right asymmetry establishment.
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Affiliation(s)
- Thomas Desvignes
- INRA, UR1037 Fish Physiology and Genomics, Campus de Beaulieu, Rennes, France IFREMER, LALR, Palavas Les Flots, France
| | - Thaovi Nguyen
- INRA, UR1037 Fish Physiology and Genomics, Campus de Beaulieu, Rennes, France
| | | | - Aurélien Bouleau
- INRA, UR1037 Fish Physiology and Genomics, Campus de Beaulieu, Rennes, France IFREMER, LALR, Palavas Les Flots, France
| | | | - Julien Bobe
- INRA, UR1037 Fish Physiology and Genomics, Campus de Beaulieu, Rennes, France
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140
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Megaw RD, Soares DC, Wright AF. RPGR: Its role in photoreceptor physiology, human disease, and future therapies. Exp Eye Res 2015; 138:32-41. [PMID: 26093275 PMCID: PMC4553903 DOI: 10.1016/j.exer.2015.06.007] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 06/03/2015] [Accepted: 06/04/2015] [Indexed: 12/21/2022]
Abstract
Mammalian photoreceptors contain specialised connecting cilia that connect the inner (IS) to the outer segments (OS). Dysfunction of the connecting cilia due to mutations in ciliary proteins are a common cause of the inherited retinal dystrophy retinitis pigmentosa (RP). Mutations affecting the Retinitis Pigmentosa GTPase Regulator (RPGR) protein is one such cause, affecting 10-20% of all people with RP and the majority of those with X-linked RP. RPGR is located in photoreceptor connecting cilia. It interacts with a wide variety of ciliary proteins, but its exact function is unknown. Recently, there have been important advances both in our understanding of RPGR function and towards the development of a therapy. This review summarises the existing literature on human RPGR function and dysfunction, and suggests that RPGR plays a role in the function of the ciliary gate, which controls access of both membrane and soluble proteins to the photoreceptor outer segment. We discuss key models used to investigate and treat RPGR disease and suggest that gene augmentation therapy offers a realistic therapeutic approach, although important questions still remain to be answered, while cell replacement therapy based on retinal progenitor cells represents a more distant prospect.
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Affiliation(s)
- Roly D Megaw
- Scottish Centre for Regenerative Medicine, University of Edinburgh, 5 Little France Drive, Edinburgh EH16 4UU, United Kingdom.
| | - Dinesh C Soares
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom.
| | - Alan F Wright
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom.
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141
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Katoh Y, Nozaki S, Hartanto D, Miyano R, Nakayama K. Architectures of multisubunit complexes revealed by a visible immunoprecipitation assay using fluorescent fusion proteins. J Cell Sci 2015; 128:2351-62. [PMID: 25964651 DOI: 10.1242/jcs.168740] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 04/30/2015] [Indexed: 12/18/2022] Open
Abstract
In this study, we elucidated the architectures of two multisubunit complexes, the BBSome and exocyst, through a novel application of fluorescent fusion proteins. By processing lysates from cells co-expressing GFP and RFP fusion proteins for immunoprecipitation with anti-GFP nanobody, protein-protein interactions could be reproducibly visualized by directly observing the immunoprecipitates under a microscope, and evaluated using a microplate reader, without requiring immunoblotting. Using this 'visible' immunoprecipitation (VIP) assay, we mapped binary subunit interactions of the BBSome complex, and determined the hierarchies of up to four subunit interactions. We also demonstrated the assembly sequence of the BBSome around the centrosome, and showed that BBS18 (also known as BBIP1 and BBIP10) serves as a linker between BBS4 and BBS8 (also known as TTC8). We also applied the VIP assay to mapping subunit interactions of the exocyst tethering complex. By individually subtracting the eight exocyst subunits from multisubunit interaction assays, we unequivocally demonstrated one-to-many subunit interactions (Exo70 with Sec10+Sec15, and Exo84 with Sec10+Sec15+Exo70). The simple, versatile VIP assay described here will pave the way to understanding the architectures and functions of multisubunit complexes involved in a variety of cellular processes.
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Affiliation(s)
- Yohei Katoh
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Shohei Nozaki
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - David Hartanto
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Rie Miyano
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Kazuhisa Nakayama
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
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142
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Hong H, Kim J, Kim J. Myosin heavy chain 10 (MYH10) is required for centriole migration during the biogenesis of primary cilia. Biochem Biophys Res Commun 2015; 461:180-5. [PMID: 25881509 DOI: 10.1016/j.bbrc.2015.04.028] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 04/04/2015] [Indexed: 01/31/2023]
Abstract
The actin cytoskeleton has been implicated in the assembly of cilia, but roles of actin-dependent motor proteins in ciliogenesis remain unclear. Myosin heavy chain 10 (MYH10), one of the isoforms of non-muscle myosin II, is known to mediate centrosome reorientation during cell migration. Here we show that MYH10 is required for centriole migration to the apical plasma membrane, which occurs at the onset of ciliogenesis. Knockdown of MYH10 in RPE1 cells caused a reduction in the levels of cortical filamentous actin (F-actin) and its binding protein EZRIN. Moreover, both centriole migration and subsequent cilium assembly were defective in MYH10 depleted cells. We further found that MYH10 influences centrosomal recruitment of IFT88, which is required for the transport of building blocks to the ciliary tip. The role of MYH10 in IFT88 recruitment appears to be indirect in that there is a correlation between centriolar IFT88 levels and centriolar positions along the apical-basal axis during ciliogenesis. Our results indicate that MYH10 contributes to ciliogenesis in RPE1 cells by promoting cortical actin-dependent centriole migration.
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Affiliation(s)
- Hyowon Hong
- Graduate School of Medical Science and Engineering, KAIST, Daejeon 305-701, Republic of Korea
| | - Jongshin Kim
- Graduate School of Medical Science and Engineering, KAIST, Daejeon 305-701, Republic of Korea
| | - Joon Kim
- Graduate School of Medical Science and Engineering, KAIST, Daejeon 305-701, Republic of Korea.
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143
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Xu Y, Cao J, Huang S, Feng D, Zhang W, Zhu X, Yan X. Characterization of tetratricopeptide repeat-containing proteins critical for cilia formation and function. PLoS One 2015; 10:e0124378. [PMID: 25860617 PMCID: PMC4393279 DOI: 10.1371/journal.pone.0124378] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 03/01/2015] [Indexed: 12/23/2022] Open
Abstract
Cilia formation and function require a special set of trafficking machinery termed intraflagellar transport (IFT), consisting mainly of protein complexes IFT-A, IFT-B, BBSome, and microtubule-dependent molecular motors. Tetratricopeptide repeat-containing (TTC) proteins are widely involved in protein complex formation. Nine of them are known to serve as components of the IFT or BBSome complexes. How many TTC proteins are cilia-related and how they function, however, remain unclear. Here we show that twenty TTC genes were upregulated by at least 2-fold during the differentiation of cultured mouse tracheal epithelial cells (MTECs) into multiciliated cells. Our systematic screen in zebrafish identified four novel TTC genes, ttc4, -9c, -36, and -39c, that are critical for cilia formation and motility. Accordingly, their zebrafish morphants displayed typical ciliopathy-related phenotypes, including curved body, abnormal otolith, hydrocephalus, and defective left-right patterning. The morphants of ttc4 and ttc25, a known cilia-related gene, additionally showed pronephric cyst formation. Immunoprecipitation indicated associations of TTC4, -9c, -25, -36, and -39c with components or entire complexes of IFT-A, IFT-B, or BBSome, implying their participations in IFT or IFT-related activities. Our results provide a global view for the relationship between TTC proteins and cilia.
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Affiliation(s)
- Yanan Xu
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai, China
| | - Jingli Cao
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai, China
| | - Shan Huang
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai, China
| | - Di Feng
- School of Life Science and Technology, ShanghaiTech University, 100 Haike Road, Shanghai, China
| | - Wei Zhang
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai, China
| | - Xueliang Zhu
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai, China
- School of Life Science and Technology, ShanghaiTech University, 100 Haike Road, Shanghai, China
- * E-mail: (XZ); (XY)
| | - Xiumin Yan
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai, China
- * E-mail: (XZ); (XY)
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Abstract
Cilia and flagella are closely related centriole-nucleated protrusions of the cell with roles in motility and signal transduction. Two of the best-studied signalling pathways organized by cilia are the transduction cascade for the morphogen Hedgehog in vertebrates and the mating pathway that initiates gamete fusion in the unicellular green alga Chlamydomonas reinhardtii. What is the role of cilia in these signalling transduction cascades? In both Hedgehog and mating pathways, all signalling intermediates have been found to localize to cilia, and, for some signalling factors, ciliary localization is regulated by pathway activation. Given a concentration factor of three orders of magnitude provided by translocating a protein into the cilium, the compartment model proposes that cilia act as miniaturized reaction tubes bringing signalling factors and processing enzymes in close proximity. On the other hand, the scaffolding model views the intraflagellar transport machinery, whose primary function is to build cilia and flagella, as a molecular scaffold for the mating transduction cascade at the flagellar membrane. While these models may coexist, it is hoped that a precise understanding of the mechanisms that govern signalling inside cilia will provide a satisfying answer to the question 'how do cilia organize signalling?'. This review covers the evidence supporting each model of signalling and outlines future directions that may address which model applies in given biological settings.
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Affiliation(s)
- Maxence V Nachury
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, CA 94305, USA
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145
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Li Y, Klena NT, Gabriel GC, Liu X, Kim AJ, Lemke K, Chen Y, Chatterjee B, Devine W, Damerla RR, Chang C, Yagi H, San Agustin JT, Thahir M, Anderton S, Lawhead C, Vescovi A, Pratt H, Morgan J, Haynes L, Smith CL, Eppig JT, Reinholdt L, Francis R, Leatherbury L, Ganapathiraju MK, Tobita K, Pazour GJ, Lo CW. Global genetic analysis in mice unveils central role for cilia in congenital heart disease. Nature 2015; 521:520-4. [PMID: 25807483 DOI: 10.1038/nature14269] [Citation(s) in RCA: 306] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 01/26/2015] [Indexed: 01/20/2023]
Abstract
Congenital heart disease (CHD) is the most prevalent birth defect, affecting nearly 1% of live births; the incidence of CHD is up to tenfold higher in human fetuses. A genetic contribution is strongly suggested by the association of CHD with chromosome abnormalities and high recurrence risk. Here we report findings from a recessive forward genetic screen in fetal mice, showing that cilia and cilia-transduced cell signalling have important roles in the pathogenesis of CHD. The cilium is an evolutionarily conserved organelle projecting from the cell surface with essential roles in diverse cellular processes. Using echocardiography, we ultrasound scanned 87,355 chemically mutagenized C57BL/6J fetal mice and recovered 218 CHD mouse models. Whole-exome sequencing identified 91 recessive CHD mutations in 61 genes. This included 34 cilia-related genes, 16 genes involved in cilia-transduced cell signalling, and 10 genes regulating vesicular trafficking, a pathway important for ciliogenesis and cell signalling. Surprisingly, many CHD genes encoded interacting proteins, suggesting that an interactome protein network may provide a larger genomic context for CHD pathogenesis. These findings provide novel insights into the potential Mendelian genetic contribution to CHD in the fetal population, a segment of the human population not well studied. We note that the pathways identified show overlap with CHD candidate genes recovered in CHD patients, suggesting that they may have relevance to the more complex genetics of CHD overall. These CHD mouse models and >8,000 incidental mutations have been sperm archived, creating a rich public resource for human disease modelling.
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Affiliation(s)
- You Li
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201, USA
| | - Nikolai T Klena
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201, USA
| | - George C Gabriel
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201, USA
| | - Xiaoqin Liu
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201, USA
| | - Andrew J Kim
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201, USA
| | - Kristi Lemke
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201, USA
| | - Yu Chen
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201, USA
| | - Bishwanath Chatterjee
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201, USA
| | - William Devine
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA
| | - Rama Rao Damerla
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201, USA
| | - Chienfu Chang
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201, USA
| | - Hisato Yagi
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201, USA
| | - Jovenal T San Agustin
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Mohamed Thahir
- 1] Department of Biomedical Informatics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15206, USA [2] Intelligent Systems Program, School of Arts and Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 16260, USA
| | - Shane Anderton
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201, USA
| | - Caroline Lawhead
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201, USA
| | - Anita Vescovi
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201, USA
| | - Herbert Pratt
- The Jackson Laboratory, Bar Harbor, Maine 04609, USA
| | - Judy Morgan
- The Jackson Laboratory, Bar Harbor, Maine 04609, USA
| | - Leslie Haynes
- The Jackson Laboratory, Bar Harbor, Maine 04609, USA
| | | | - Janan T Eppig
- The Jackson Laboratory, Bar Harbor, Maine 04609, USA
| | | | - Richard Francis
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201, USA
| | - Linda Leatherbury
- The Heart Center, Children's National Medical Center, Washington DC 20010, USA
| | - Madhavi K Ganapathiraju
- 1] Department of Biomedical Informatics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15206, USA [2] Intelligent Systems Program, School of Arts and Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 16260, USA
| | - Kimimasa Tobita
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201, USA
| | - Gregory J Pazour
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Cecilia W Lo
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201, USA
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146
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Alternative Splicing Shapes the Phenotype of a Mutation in BBS8 To Cause Nonsyndromic Retinitis Pigmentosa. Mol Cell Biol 2015; 35:1860-70. [PMID: 25776555 DOI: 10.1128/mcb.00040-15] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 03/10/2015] [Indexed: 01/27/2023] Open
Abstract
Bardet-Biedl syndrome (BBS) is a genetic disorder affecting multiple systems and organs in the body. Several mutations in genes associated with BBS affect only photoreceptor cells and cause nonsyndromic retinitis pigmentosa (RP), raising the issue of why certain mutations manifest as a systemic disorder whereas other changes in the same gene affect only a specific cell type. Here, we show that cell-type-specific alternative splicing is responsible for confining the phenotype of the A-to-G substitution in the 3' splice site of BBS8 exon 2A (IVS1-2A>G mutation) in the BBS8 gene to photoreceptor cells. The IVS1-2A>G mutation leads to missplicing of BBS8 exon 2A, producing a frameshift in the BBS8 reading frame and thus eliminating the protein specifically in photoreceptor cells. Cell types other than photoreceptors skip exon 2A from the mature BBS8 transcript, which renders them immune to the mutation. We also show that the splicing of Bbs8 exon 2A in photoreceptors is directed exclusively by redundant splicing enhancers located in the adjacent introns. These intronic sequences are sufficient for photoreceptor-cell-specific splicing of heterologous exons, including an exon with a randomized sequence.
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147
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Ciliary ectosomes: transmissions from the cell's antenna. Trends Cell Biol 2015; 25:276-85. [PMID: 25618328 DOI: 10.1016/j.tcb.2014.12.008] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 12/20/2014] [Accepted: 12/22/2014] [Indexed: 12/21/2022]
Abstract
The cilium is the site of function for a variety of membrane receptors, enzymes and signal transduction modules crucial for a spectrum of cellular processes. Through targeted transport and selective gating mechanisms, the cell localizes specific proteins to the cilium that equip it for the role of sensory antenna. This capacity of the cilium to serve as a specialized compartment where specific proteins can be readily concentrated for sensory reception also makes it an ideal organelle to employ for the regulated emission of specific biological material and information. In this review we present and discuss an emerging body of evidence centered on ciliary ectosomes - bioactive vesicles released from the surface of the cilium.
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148
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Diener DR, Lupetti P, Rosenbaum JL. Proteomic analysis of isolated ciliary transition zones reveals the presence of ESCRT proteins. Curr Biol 2015; 25:379-384. [PMID: 25578910 DOI: 10.1016/j.cub.2014.11.066] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 11/13/2014] [Accepted: 11/20/2014] [Indexed: 10/24/2022]
Abstract
The transition zone (TZ) is a specialized region of the cilium characterized by Y-shaped connectors between the microtubules of the ciliary axoneme and the ciliary membrane [1]. Located near the base of the cilium, the TZ is in the prime location to act as a gate for proteins into and out of the ciliary compartment, a role supported by experimental evidence [2-6]. The importance of the TZ has been underscored by studies showing that mutations affecting proteins located in the TZ result in cilia-related diseases, or ciliopathies, presenting symptoms including renal cysts, retinal degeneration, and situs inversus [7-9]. Some TZ proteins have been identified and shown to interact with each other through coprecipitation studies in vertebrate cells [4, 10, 11] and genetics studies in C. elegans [3]. As a distinct approach to identify TZ proteins, we have taken advantage of the biology of Chlamydomonas to isolate TZs. Proteomic analysis identified 115 proteins, ten of which were known TZ proteins related to ciliopathies, indicating that the preparation was highly enriched for TZs. Interestingly, six proteins of the endosomal sorting complexes required for transport (ESCRT) were also associated with the TZs. Identification of these and other proteins in the TZ will provide new insights into functions of the TZ, as well as candidate ciliopathy genes.
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Affiliation(s)
- Dennis R Diener
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06511, USA.
| | - Pietro Lupetti
- Department of Life Sciences, University of Siena, Siena 53100, Italy
| | - Joel L Rosenbaum
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06511, USA.
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149
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Abstract
Primary cilia are essential cellular organelles projecting from the cell surface to sense and transduce developmental signaling. They are tiny but have complicated structures containing microtubule (MT)-based internal structures (the axoneme) and mother centriole formed basal body. Intraflagellar transport (Ift) operated by Ift proteins and motors are indispensable for cilia formation and function. Mutations in Ift proteins or Ift motors cause various human diseases, some of which have severe bone defects. Over the last few decades, major advances have occurred in understanding the roles of these proteins and cilia in bone development and remodeling by examining cilia/Ift protein-related human diseases and establishing mouse transgenic models. In this review, we describe current advances in the understanding of the cilia/Ift structure and function. We further summarize cilia/Ift-related human diseases and current mouse models with an emphasis on bone-related phenotypes, cilia morphology, and signaling pathways.
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Affiliation(s)
- Xue Yuan
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, The State University of New York, 3435 Main Street, Buffalo, NY, 14214, USA
| | - Shuying Yang
- Department of Oral Biology, School of Dental Medicine, University at Buffalo, The State University of New York, 3435 Main Street, Buffalo, NY, 14214, USA
- Developmental Genomics Group, New York State Center of Excellence in Bioinformatics and Life Sciences, University at Buffalo, The State University of New York, 701 Ellicott St, Buffalo, NY, 14203, USA
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150
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Mourão A, Nager AR, Nachury MV, Lorentzen E. Structural basis for membrane targeting of the BBSome by ARL6. Nat Struct Mol Biol 2014; 21:1035-41. [PMID: 25402481 PMCID: PMC4255524 DOI: 10.1038/nsmb.2920] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 10/20/2014] [Indexed: 12/16/2022]
Abstract
The BBSome is a coat-like ciliary trafficking complex composed of proteins mutated in Bardet-Biedl syndrome (BBS). A critical step in BBSome-mediated sorting is recruitment of the BBSome to membranes by the GTP-bound Arf-like GTPase ARL6. We have determined crystal structures of Chlamydomonas reinhardtii ARL6-GDP, ARL6-GTP and the ARL6-GTP-BBS1 complex. The structures demonstrate how ARL6-GTP binds the BBS1 β-propeller at blades 1 and 7 and explain why GTP- but not GDP-bound ARL6 can recruit the BBSome to membranes. Single point mutations in the ARL6-GTP-BBS1 interface abolish the interaction of ARL6 with the BBSome and prevent the import of BBSomes into cilia. Furthermore, we show that BBS1 with the M390R mutation, responsible for 30% of all reported BBS disease cases, fails to interact with ARL6-GTP, thus providing a molecular rationale for patient pathologies.
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Affiliation(s)
- André Mourão
- Department of Structural Cell Biology, Max-Planck-Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany
| | - Andrew R. Nager
- Department of Molecular and Cellular Physiology, Stanford University, School of Medicine, Stanford, CA 94305
| | - Maxence V. Nachury
- Department of Molecular and Cellular Physiology, Stanford University, School of Medicine, Stanford, CA 94305
| | - Esben Lorentzen
- Department of Structural Cell Biology, Max-Planck-Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany
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