1
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Xu Y, Muñoz-Hernández H, Krutyhołowa R, Marxer F, Cetin F, Wieczorek M. Partial closure of the γ-tubulin ring complex by CDK5RAP2 activates microtubule nucleation. Dev Cell 2024:S1534-5807(24)00530-6. [PMID: 39321808 DOI: 10.1016/j.devcel.2024.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 06/04/2024] [Accepted: 09/03/2024] [Indexed: 09/27/2024]
Abstract
Microtubule nucleation is templated by the γ-tubulin ring complex (γ-TuRC), but its structure deviates from the geometry of α-/β-tubulin in the microtubule, explaining the complex's poor nucleating activity. Several proteins may activate the γ-TuRC, but the mechanisms underlying activation are not known. Here, we determined the structure of the porcine γ-TuRC purified using CDK5RAP2's centrosomin motif 1 (CM1). We identified an unexpected conformation of the γ-TuRC bound to multiple protein modules containing MZT2, GCP2, and CDK5RAP2, resulting in a long-range constriction of the γ-tubulin ring that brings it in closer agreement with the 13-protofilament microtubule. Additional CDK5RAP2 promoted γ-TuRC decoration and stimulated the microtubule-nucleating activities of the porcine γ-TuRC and a reconstituted, CM1-free human complex in single-molecule assays. Our results provide a structural mechanism for the control of microtubule nucleation by CM1 proteins and identify conformational transitions in the γ-TuRC that prime it for microtubule nucleation.
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Affiliation(s)
- Yixin Xu
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zürich, 8093 Zürich, Switzerland
| | - Hugo Muñoz-Hernández
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zürich, 8093 Zürich, Switzerland
| | - Rościsław Krutyhołowa
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zürich, 8093 Zürich, Switzerland
| | - Florina Marxer
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zürich, 8093 Zürich, Switzerland
| | - Ferdane Cetin
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zürich, 8093 Zürich, Switzerland
| | - Michal Wieczorek
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zürich, 8093 Zürich, Switzerland.
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2
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Chen JS, Igarashi MG, Ren L, Hanna SM, Turner LA, McDonald NA, Beckley JR, Willet AH, Gould KL. The core spindle pole body scaffold Ppc89 links the pericentrin orthologue Pcp1 to the fission yeast spindle pole body via an evolutionarily conserved interface. Mol Biol Cell 2024; 35:ar112. [PMID: 38985524 PMCID: PMC11321043 DOI: 10.1091/mbc.e24-05-0220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2024] [Revised: 06/26/2024] [Accepted: 07/02/2024] [Indexed: 07/12/2024] Open
Abstract
Centrosomes and spindle pole bodies (SPBs) are important for mitotic spindle formation and serve as cellular signaling platforms. Although centrosomes and SPBs differ in morphology, many mechanistic insights into centrosome function have been gleaned from SPB studies. In the fission yeast Schizosaccharomyces pombe, the α-helical protein Ppc89, identified based on its interaction with the septation initiation network scaffold Sid4, comprises the SPB core. High-resolution imaging has suggested that SPB proteins assemble on the Ppc89 core during SPB duplication, but such interactions are undefined. Here, we define a connection between Ppc89 and the essential pericentrin Pcp1. Specifically, we found that a predicted third helix within Ppc89 binds the Pcp1 pericentrin-AKAP450 centrosomal targeting (PACT) domain complexed with calmodulin. Ppc89 helix 3 contains similarity to present in the N-terminus of Cep57 (PINC) motifs found in the centrosomal proteins fly SAS-6 and human Cep57 and also to the S. cerevisiae SPB protein Spc42. These motifs bind pericentrin-calmodulin complexes and AlphaFold2 models suggest a homologous complex assembles in all four organisms. Mutational analysis of the S. pombe complex supports the importance of Ppc89-Pcp1 binding interface in vivo. Our studies provide insight into the core architecture of the S. pombe SPB and suggest an evolutionarily conserved mechanism of scaffolding pericentrin-calmodulin complexes for mitotic spindle formation.
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Affiliation(s)
- Jun-Song Chen
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240
| | - Maya G. Igarashi
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240
| | - Liping Ren
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240
| | - Sarah M. Hanna
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240
| | - Lesley A. Turner
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240
| | - Nathan A. McDonald
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240
| | - Janel R. Beckley
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240
| | - Alaina H. Willet
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240
| | - Kathleen L. Gould
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37240
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3
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Rollins KR, Blankenship JT. Dysregulation of the endoplasmic reticulum blocks recruitment of centrosome-associated proteins resulting in mitotic failure. Development 2023; 150:dev201917. [PMID: 37971218 PMCID: PMC10690056 DOI: 10.1242/dev.201917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 10/17/2023] [Indexed: 11/19/2023]
Abstract
The endoplasmic reticulum (ER) undergoes a remarkable transition in morphology during cell division to aid in the proper portioning of the ER. However, whether changes in ER behaviors modulate mitotic events is less clear. Like many animal embryos, the early Drosophila embryo undergoes rapid cleavage cycles in a lipid-rich environment. Here, we show that mitotic spindle formation, centrosomal maturation, and ER condensation occur with similar time frames in the early syncytium. In a screen for Rab family GTPases that display dynamic function at these stages, we identified Rab1. Rab1 disruption led to an enhanced buildup of ER at the spindle poles and produced an intriguing 'mini-spindle' phenotype. ER accumulation around the mitotic space negatively correlates with spindle length/intensity. Importantly, centrosomal maturation is defective in these embryos, as mitotic recruitment of key centrosomal proteins is weakened after Rab1 disruption. Finally, division failures and ER overaccumulation is rescued by Dynein inhibition, demonstrating that Dynein is essential for ER spindle recruitment. These results reveal that ER levels must be carefully tuned during mitotic processes to ensure proper assembly of the division machinery.
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Affiliation(s)
| | - J. Todd Blankenship
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
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4
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Zhu Z, Becam I, Tovey CA, Elfarkouchi A, Yen EC, Bernard F, Guichet A, Conduit PT. Multifaceted modes of γ-tubulin complex recruitment and microtubule nucleation at mitotic centrosomes. J Cell Biol 2023; 222:e202212043. [PMID: 37698931 PMCID: PMC10497398 DOI: 10.1083/jcb.202212043] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 05/18/2023] [Accepted: 07/24/2023] [Indexed: 09/14/2023] Open
Abstract
Microtubule nucleation is mediated by γ-tubulin ring complexes (γ-TuRCs). In most eukaryotes, a GCP4/5/4/6 "core" complex promotes γ-tubulin small complex (γ-TuSC) association to generate cytosolic γ-TuRCs. Unlike γ-TuSCs, however, this core complex is non-essential in various species and absent from budding yeasts. In Drosophila, Spindle defective-2 (Spd-2) and Centrosomin (Cnn) redundantly recruit γ-tubulin complexes to mitotic centrosomes. Here, we show that Spd-2 recruits γ-TuRCs formed via the GCP4/5/4/6 core, but Cnn can recruit γ-TuSCs directly via its well-conserved CM1 domain, similar to its homologs in budding yeast. When centrosomes fail to recruit γ-tubulin complexes, they still nucleate microtubules via the TOG domain protein Mini-spindles (Msps), but these microtubules have different dynamic properties. Our data, therefore, help explain the dispensability of the GCP4/5/4/6 core and highlight the robustness of centrosomes as microtubule organizing centers. They also suggest that the dynamic properties of microtubules are influenced by how they are nucleated.
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Affiliation(s)
- Zihan Zhu
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Isabelle Becam
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | - Corinne A. Tovey
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | - Abir Elfarkouchi
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | - Eugenie C. Yen
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Fred Bernard
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | - Antoine Guichet
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | - Paul T. Conduit
- Department of Zoology, University of Cambridge, Cambridge, UK
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
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5
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Yang S, Au FK, Li G, Lin J, Li XD, Qi RZ. Autoinhibitory mechanism controls binding of centrosomin motif 1 to γ-tubulin ring complex. J Cell Biol 2023; 222:e202007101. [PMID: 37213089 PMCID: PMC10202828 DOI: 10.1083/jcb.202007101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 01/03/2023] [Accepted: 03/24/2023] [Indexed: 05/23/2023] Open
Abstract
The γ-tubulin ring complex (γTuRC) is the principal nucleator of cellular microtubules, and the microtubule-nucleating activity of the complex is stimulated by binding to the γTuRC-mediated nucleation activator (γTuNA) motif. The γTuNA is part of the centrosomin motif 1 (CM1), which is widely found in γTuRC stimulators, including CDK5RAP2. Here, we show that a conserved segment within CM1 binds to the γTuNA and blocks its association with γTuRCs; therefore, we refer to this segment as the γTuNA inhibitor (γTuNA-In). Mutational disruption of the interaction between the γTuNA and the γTuNA-In results in a loss of autoinhibition, which consequently augments microtubule nucleation on centrosomes and the Golgi complex, the two major microtubule-organizing centers. This also causes centrosome repositioning, leads to defects in Golgi assembly and organization, and affects cell polarization. Remarkably, phosphorylation of the γTuNA-In, probably by Nek2, counteracts the autoinhibition by disrupting the γTuNA‒γTuNA-In interaction. Together, our data reveal an on-site mechanism for controlling γTuNA function.
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Affiliation(s)
- Shaozhong Yang
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Franco K.C. Au
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Gefei Li
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Jianwei Lin
- Department of Chemistry, The University of Hong Kong, Hong Kong, China
| | - Xiang David Li
- Department of Chemistry, The University of Hong Kong, Hong Kong, China
| | - Robert Z. Qi
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Hong Kong, China
- Bioscience and Biomedical Engineering Thrust, The Hong Kong University of Science and Technology (Guangzhou), Guangzhou, China
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6
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Ali A, Vineethakumari C, Lacasa C, Lüders J. Microtubule nucleation and γTuRC centrosome localization in interphase cells require ch-TOG. Nat Commun 2023; 14:289. [PMID: 36702836 PMCID: PMC9879976 DOI: 10.1038/s41467-023-35955-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Accepted: 01/10/2023] [Indexed: 01/27/2023] Open
Abstract
Organization of microtubule arrays requires spatio-temporal regulation of the microtubule nucleator γ-tubulin ring complex (γTuRC) at microtubule organizing centers (MTOCs). MTOC-localized adapter proteins are thought to recruit and activate γTuRC, but the molecular underpinnings remain obscure. Here we show that at interphase centrosomes, rather than adapters, the microtubule polymerase ch-TOG (also named chTOG or CKAP5) ultimately controls γTuRC recruitment and activation. ch-TOG co-assembles with γTuRC to stimulate nucleation around centrioles. In the absence of ch-TOG, γTuRC fails to localize to these sites, but not the centriole lumen. However, whereas some ch-TOG is stably bound at subdistal appendages, it only transiently associates with PCM. ch-TOG's dynamic behavior requires its tubulin-binding TOG domains and a C-terminal region involved in localization. In addition, ch-TOG also promotes nucleation from the Golgi. Thus, at interphase centrosomes stimulation of nucleation and γTuRC attachment are mechanistically coupled through transient recruitment of ch-TOG, and ch-TOG's nucleation-promoting activity is not restricted to centrosomes.
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Affiliation(s)
- Aamir Ali
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, 08028, Spain
| | - Chithran Vineethakumari
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, 08028, Spain
| | - Cristina Lacasa
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, 08028, Spain
| | - Jens Lüders
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, 08028, Spain.
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7
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Hirai K, Inoue YH, Matsuda M. Mitotic progression and dual spindle formation caused by spindle association of de novo-formed microtubule-organizing centers in parthenogenetic embryos of Drosophila ananassae. Genetics 2022; 223:6896485. [PMID: 36516293 PMCID: PMC9910410 DOI: 10.1093/genetics/iyac178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Revised: 09/17/2022] [Accepted: 11/22/2022] [Indexed: 12/15/2022] Open
Abstract
Facultative parthenogenesis occurs in many animal species that typically undergo sexual reproduction. In Drosophila, such development from unfertilized eggs involves diploidization after completion of meiosis, but the exact mechanism remains unclear. Here we used a laboratory stock of Drosophila ananassae that has been maintained parthenogenetically to cytologically examine the initial events of parthenogenesis. Specifically, we determined whether the requirements for centrosomes and diploidization that are essential for developmental success can be overcome. As a primal deviation from sexually reproducing (i.e. sexual) strains of the same species, free asters emerged from the de novo formation of centrosome-like structures in the cytosol of unfertilized eggs. Those microtubule-organizing centers had distinct roles in the earliest cycles of parthenogenetic embryos with respect to mitotic progression and arrangement of mitotic spindles. In the first cycle, an anastral bipolar spindle self-assembled around a haploid set of replicated chromosomes. Participation of at least one microtubule-organizing center in the spindle was necessary for mitotic progression into anaphase. In particular, the first mitosis involving a monastral bipolar spindle resulted in haploid daughter nuclei, one of which was associated with a microtubule-organizing center whereas the other was not. Remarkably, in the following cycle, biastral and anastral bipolar spindles formed that were frequently arranged in tandem by sharing an aster with bidirectional connections at their central poles. We propose that, for diploidization of haploid nuclei, unfertilized parthenogenetic embryos utilize dual spindles during the second mitosis, as occurs for the first mitosis in normal fertilized eggs.
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Affiliation(s)
| | - Yoshihiro H Inoue
- Biomedical Research Center, Kyoto Institute of Technology, Kyoto, Kyoto 606-8585, Japan
| | - Muneo Matsuda
- Department of Biology, Kyorin University School of Medicine, Mitaka, Tokyo 181-8611, Japan
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8
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Thomas A, Giet R. Live imaging of Drosophila melanogaster neural stem cells with photo-ablated centrosomes. STAR Protoc 2022; 3:101493. [PMID: 35776653 PMCID: PMC9249821 DOI: 10.1016/j.xpro.2022.101493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 04/26/2022] [Accepted: 06/03/2022] [Indexed: 11/17/2022] Open
Affiliation(s)
- Alexandre Thomas
- Univ Rennes, CNRS, INSERM, IGDR (Institut de Génétique et Développement de Rennes)-UMR6290, ERL U1305, 35000 Rennes, France
| | - Régis Giet
- Univ Rennes, CNRS, INSERM, IGDR (Institut de Génétique et Développement de Rennes)-UMR6290, ERL U1305, 35000 Rennes, France.
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9
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Nakajo M, Kano H, Tsuyama K, Haruta N, Sugimoto A. Centrosome maturation requires phosphorylation-mediated sequential domain interactions of SPD-5. J Cell Sci 2022; 135:274944. [PMID: 35362532 DOI: 10.1242/jcs.259025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 03/18/2022] [Indexed: 11/20/2022] Open
Abstract
Centrosomes consist of two centrioles and surrounding pericentriolar material (PCM). PCM expands during mitosis in a process called centrosome maturation, in which PCM scaffold proteins play pivotal roles to recruit other centrosomal proteins. In C. elegans, the scaffold protein SPD-5 forms PCM scaffold in a PLK-1 phosphorylation-dependent manner. However, how phosphorylation of SPD-5 promotes PCM scaffold assembly is unclear. Here, we identified three functional domains of SPD-5 through in vivo domain analyses, and propose that sequential domain interactions of SPD-5 are required for mitotic PCM scaffold assembly. Firstly, SPD-5 is targeted to centrioles through direct interaction between its centriole localization (CL) domain and a centriolar protein PCMD-1. Then, intra- and intermolecular interaction between SPD-5 phospho-regulated multimerization (PReM) domain and the PReM association (PA) domain is enhanced by phosphorylation by PLK-1, which leads to PCM scaffold expansion. Our findings suggest that the sequential domain interactions of scaffold proteins mediated by Polo/PLK-1 phosphorylation is an evolutionarily conserved mechanism of PCM scaffold assembly.
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Affiliation(s)
- Momoe Nakajo
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Hikaru Kano
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Kenji Tsuyama
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Nami Haruta
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Asako Sugimoto
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
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10
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Ryniawec JM, Rogers GC. Centrosome instability: when good centrosomes go bad. Cell Mol Life Sci 2021; 78:6775-6795. [PMID: 34476544 PMCID: PMC8560572 DOI: 10.1007/s00018-021-03928-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 08/10/2021] [Accepted: 08/26/2021] [Indexed: 02/06/2023]
Abstract
The centrosome is a tiny cytoplasmic organelle that organizes and constructs massive molecular machines to coordinate diverse cellular processes. Due to its many roles during both interphase and mitosis, maintaining centrosome homeostasis is essential to normal health and development. Centrosome instability, divergence from normal centrosome number and structure, is a common pathognomonic cellular state tightly associated with cancers and other genetic diseases. As novel connections are investigated linking the centrosome to disease, it is critical to understand the breadth of centrosome functions to inspire discovery. In this review, we provide an introduction to normal centrosome function and highlight recent discoveries that link centrosome instability to specific disease states.
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Affiliation(s)
- John M Ryniawec
- University of Arizona Cancer Center, University of Arizona, 1515 N. Campbell Ave., Tucson, AZ, 85724, USA
| | - Gregory C Rogers
- University of Arizona Cancer Center, University of Arizona, 1515 N. Campbell Ave., Tucson, AZ, 85724, USA.
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11
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Alzyoud E, Vedelek V, Réthi-Nagy Z, Lipinszki Z, Sinka R. Microtubule Organizing Centers Contain Testis-Specific γ-TuRC Proteins in Spermatids of Drosophila. Front Cell Dev Biol 2021; 9:727264. [PMID: 34660584 PMCID: PMC8511327 DOI: 10.3389/fcell.2021.727264] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 09/10/2021] [Indexed: 11/17/2022] Open
Abstract
Microtubule nucleation in eukaryotes is primarily promoted by γ-tubulin and the evolutionary conserved protein complex, γ-Tubulin Ring Complex (γ-TuRC). γ-TuRC is part of the centrosome and basal body, which are the best-known microtubule-organizing centers. Centrosomes undergo intensive and dynamic changes during spermatogenesis, as they turn into basal bodies, a prerequisite for axoneme formation during spermatogenesis. Here we describe the existence of a novel, tissue-specific γ-TuRC in Drosophila. We characterize three genes encoding testis-specific components of γ-TuRC (t-γ-TuRC) and find that presence of t-γ-TuRC is essential to male fertility. We show the diverse subcellular distribution of the t-γ-TuRC proteins during post-meiotic development, at first at the centriole adjunct and then also on the anterior tip of the nucleus, and finally, they appear in the tail region, close to the mitochondria. We also prove the physical interactions between the t-γ-TuRC members, γ-tubulin and Mozart1. Our results further indicate heterogeneity in γ-TuRC composition during spermatogenesis and suggest that the different post-meiotic microtubule organizing centers are orchestrated by testis-specific gene products, including t-γ-TuRC.
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Affiliation(s)
- Elham Alzyoud
- Department of Genetics, University of Szeged, Szeged, Hungary
- Faculty of Science and Informatics, Doctoral School of Biology, University of Szeged, Szeged, Hungary
| | - Viktor Vedelek
- Department of Genetics, University of Szeged, Szeged, Hungary
| | - Zsuzsánna Réthi-Nagy
- Faculty of Science and Informatics, Doctoral School of Biology, University of Szeged, Szeged, Hungary
- Biological Research Centre, Institute of Biochemistry, MTA SZBK Lendület Laboratory of Cell Cycle Regulation, Eötvös Loránd Research Network (ELKH), Szeged, Hungary
| | - Zoltán Lipinszki
- Biological Research Centre, Institute of Biochemistry, MTA SZBK Lendület Laboratory of Cell Cycle Regulation, Eötvös Loránd Research Network (ELKH), Szeged, Hungary
| | - Rita Sinka
- Department of Genetics, University of Szeged, Szeged, Hungary
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12
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Chen S, Alhassen W, Vakil Monfared R, Vachirakorntong B, Nauli SM, Baldi P, Alachkar A. Dynamic Changes of Brain Cilia Transcriptomes across the Human Lifespan. Int J Mol Sci 2021; 22:10387. [PMID: 34638726 PMCID: PMC8509004 DOI: 10.3390/ijms221910387] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 09/23/2021] [Accepted: 09/24/2021] [Indexed: 12/27/2022] Open
Abstract
Almost all brain cells contain primary cilia, antennae-like microtubule sensory organelles, on their surface, which play critical roles in brain functions. During neurodevelopmental stages, cilia are essential for brain formation and maturation. In the adult brain, cilia play vital roles as signaling hubs that receive and transduce various signals and regulate cell-to-cell communications. These distinct roles suggest that cilia functions, and probably structures, change throughout the human lifespan. To further understand the age-dependent changes in cilia roles, we identified and analyzed age-dependent patterns of expression of cilia's structural and functional components across the human lifespan. We acquired cilia transcriptomic data for 16 brain regions from the BrainSpan Atlas and analyzed the age-dependent expression patterns using a linear regression model by calculating the regression coefficient. We found that 67% of cilia transcripts were differentially expressed genes with age (DEGAs) in at least one brain region. The age-dependent expression was region-specific, with the highest and lowest numbers of DEGAs expressed in the ventrolateral prefrontal cortex and hippocampus, respectively. The majority of cilia DEGAs displayed upregulation with age in most of the brain regions. The transcripts encoding cilia basal body components formed the majority of cilia DEGAs, and adjacent cerebral cortices exhibited large overlapping pairs of cilia DEGAs. Most remarkably, specific α/β-tubulin subunits (TUBA1A, TUBB2A, and TUBB2B) and SNAP-25 exhibited the highest rates of downregulation and upregulation, respectively, across age in almost all brain regions. α/β-tubulins and SNAP-25 expressions are known to be dysregulated in age-related neurodevelopmental and neurodegenerative disorders. Our results support a role for the high dynamics of cilia structural and functional components across the lifespan in the normal physiology of brain circuits. Furthermore, they suggest a crucial role for cilia signaling in the pathophysiological mechanisms of age-related psychiatric/neurological disorders.
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Affiliation(s)
- Siwei Chen
- Department of Computer Science, School of Information and Computer Sciences, University of California-Irvine, Irvine, CA 92617, USA; (S.C.); (P.B.)
- Institute for Genomics and Bioinformatics, School of Information and Computer Sciences, University of California-Irvine, Irvine, CA 92617, USA
| | - Wedad Alhassen
- Department of Pharmaceutical Sciences, School of Pharmacy, University of California-Irvine, Irvine, CA 92617, USA; (W.A.); (R.V.M.); (B.V.)
| | - Roudabeh Vakil Monfared
- Department of Pharmaceutical Sciences, School of Pharmacy, University of California-Irvine, Irvine, CA 92617, USA; (W.A.); (R.V.M.); (B.V.)
| | - Benjamin Vachirakorntong
- Department of Pharmaceutical Sciences, School of Pharmacy, University of California-Irvine, Irvine, CA 92617, USA; (W.A.); (R.V.M.); (B.V.)
| | - Surya M. Nauli
- Department of Biomedical and Pharmaceutical Sciences, School of Pharmacy, Chapman University Rinker Health Science Campus, Irvine, CA 92618, USA;
| | - Pierre Baldi
- Department of Computer Science, School of Information and Computer Sciences, University of California-Irvine, Irvine, CA 92617, USA; (S.C.); (P.B.)
- Institute for Genomics and Bioinformatics, School of Information and Computer Sciences, University of California-Irvine, Irvine, CA 92617, USA
| | - Amal Alachkar
- Institute for Genomics and Bioinformatics, School of Information and Computer Sciences, University of California-Irvine, Irvine, CA 92617, USA
- Department of Pharmaceutical Sciences, School of Pharmacy, University of California-Irvine, Irvine, CA 92617, USA; (W.A.); (R.V.M.); (B.V.)
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13
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Abstract
As one of four filament types, microtubules are a core component of the cytoskeleton and are essential for cell function. Yet how microtubules are nucleated from their building blocks, the αβ-tubulin heterodimer, has remained a fundamental open question since the discovery of tubulin 50 years ago. Recent structural studies have shed light on how γ-tubulin and the γ-tubulin complex proteins (GCPs) GCP2 to GCP6 form the γ-tubulin ring complex (γ-TuRC). In parallel, functional and single-molecule studies have informed on how the γ-TuRC nucleates microtubules in real time, how this process is regulated in the cell and how it compares to other modes of nucleation. Another recent surprise has been the identification of a second essential nucleation factor, which turns out to be the well-characterized microtubule polymerase XMAP215 (also known as CKAP5, a homolog of chTOG, Stu2 and Alp14). This discovery helps to explain why the observed nucleation activity of the γ-TuRC in vitro is relatively low. Taken together, research in recent years has afforded important insight into how microtubules are made in the cell and provides a basis for an exciting era in the cytoskeleton field.
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Affiliation(s)
- Akanksha Thawani
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, Berkeley, CA 94720, USA
| | - Sabine Petry
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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14
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A release-and-capture mechanism generates an essential non-centrosomal microtubule array during tube budding. Nat Commun 2021; 12:4096. [PMID: 34215746 PMCID: PMC8253823 DOI: 10.1038/s41467-021-24332-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 05/27/2021] [Indexed: 11/08/2022] Open
Abstract
Non-centrosomal microtubule arrays serve crucial functions in cells, yet the mechanisms of their generation are poorly understood. During budding of the epithelial tubes of the salivary glands in the Drosophila embryo, we previously demonstrated that the activity of pulsatile apical-medial actomyosin depends on a longitudinal non-centrosomal microtubule array. Here we uncover that the exit from the last embryonic division cycle of the epidermal cells of the salivary gland placode leads to one centrosome in the cells losing all microtubule-nucleation capacity. This restriction of nucleation activity to the second, Centrobin-enriched, centrosome is key for proper morphogenesis. Furthermore, the microtubule-severing protein Katanin and the minus-end-binding protein Patronin accumulate in an apical-medial position only in placodal cells. Loss of either in the placode prevents formation of the longitudinal microtubule array and leads to loss of apical-medial actomyosin and impaired apical constriction. We thus propose a mechanism whereby Katanin-severing at the single active centrosome releases microtubule minus-ends that are then anchored by apical-medial Patronin to promote formation of the longitudinal microtubule array crucial for apical constriction and tube formation.
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15
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Wang XF, Yang SA, Gong S, Chang CH, Portilla JM, Chatterjee D, Irianto J, Bao H, Huang YC, Deng WM. Polyploid mitosis and depolyploidization promote chromosomal instability and tumor progression in a Notch-induced tumor model. Dev Cell 2021; 56:1976-1988.e4. [PMID: 34146466 DOI: 10.1016/j.devcel.2021.05.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 03/18/2021] [Accepted: 05/27/2021] [Indexed: 02/07/2023]
Abstract
Ploidy variation is a cancer hallmark and is frequently associated with poor prognosis in high-grade cancers. Using a Drosophila solid-tumor model where oncogenic Notch drives tumorigenesis in a transition-zone microenvironment in the salivary gland imaginal ring, we find that the tumor-initiating cells normally undergo endoreplication to become polyploid. Upregulation of Notch signaling, however, induces these polyploid transition-zone cells to re-enter mitosis and undergo tumorigenesis. Growth and progression of the transition-zone tumor are fueled by a combination of polyploid mitosis, endoreplication, and depolyploidization. Both polyploid mitosis and depolyploidization are error prone, resulting in chromosomal copy-number variation and polyaneuploidy. Comparative RNA-seq and epistasis analysis reveal that the DNA-damage response genes, also active during meiosis, are upregulated in these tumors and are required for the ploidy-reduction division. Together, these findings suggest that polyploidy and associated cell-cycle variants are critical for increased tumor-cell heterogeneity and genome instability during cancer progression.
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Affiliation(s)
- Xian-Feng Wang
- Department of Biochemistry and Molecular Biology, Tulane University Louisiana Center Research Center, New Orleans, LA 70112, USA
| | - Sheng-An Yang
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Shangyu Gong
- Department of Biochemistry and Molecular Biology, Tulane University Louisiana Center Research Center, New Orleans, LA 70112, USA
| | - Chih-Hsuan Chang
- Department of Biochemistry and Molecular Biology, Tulane University Louisiana Center Research Center, New Orleans, LA 70112, USA
| | - Juan Martin Portilla
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Deeptiman Chatterjee
- Department of Biochemistry and Molecular Biology, Tulane University Louisiana Center Research Center, New Orleans, LA 70112, USA
| | - Jerome Irianto
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL 32306, USA
| | - Hongcun Bao
- Department of Biochemistry and Molecular Biology, Tulane University Louisiana Center Research Center, New Orleans, LA 70112, USA
| | - Yi-Chun Huang
- Department of Biochemistry and Molecular Biology, Tulane University Louisiana Center Research Center, New Orleans, LA 70112, USA
| | - Wu-Min Deng
- Department of Biochemistry and Molecular Biology, Tulane University Louisiana Center Research Center, New Orleans, LA 70112, USA; Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA.
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16
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Tovey CA, Tsuji C, Egerton A, Bernard F, Guichet A, de la Roche M, Conduit PT. Autoinhibition of Cnn binding to γ-TuRCs prevents ectopic microtubule nucleation and cell division defects. J Cell Biol 2021; 220:212197. [PMID: 34042945 PMCID: PMC8164090 DOI: 10.1083/jcb.202010020] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 03/25/2021] [Accepted: 05/05/2021] [Indexed: 12/22/2022] Open
Abstract
γ-Tubulin ring complexes (γ-TuRCs) nucleate microtubules. They are recruited to centrosomes in dividing cells via binding to N-terminal CM1 domains within γ-TuRC–tethering proteins, including Drosophila Centrosomin (Cnn). Binding promotes microtubule nucleation and is restricted to centrosomes in dividing cells, but the mechanism regulating binding remains unknown. Here, we identify an extreme N-terminal CM1 autoinhibition (CAI) domain found specifically within the centrosomal isoform of Cnn (Cnn-C) that inhibits γ-TuRC binding. Robust binding occurs after removal of the CAI domain or with the addition of phosphomimetic mutations, suggesting that phosphorylation helps relieve inhibition. We show that regulation of Cnn binding to γ-TuRCs is isoform specific and that misregulation of binding can result in ectopic cytosolic microtubules and major defects during cell division. We also find that human CDK5RAP2 is autoinhibited from binding γ-TuRCs, suggesting conservation across species. Overall, our results shed light on how and why CM1 domain binding to γ-TuRCs is regulated.
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Affiliation(s)
- Corinne A Tovey
- Department of Zoology, University of Cambridge, Cambridge, UK.,Université de Paris, Centre National de la Recherche Scientifique, Institut Jacques Monod, Paris, France
| | - Chisato Tsuji
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Alice Egerton
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Fred Bernard
- Université de Paris, Centre National de la Recherche Scientifique, Institut Jacques Monod, Paris, France
| | - Antoine Guichet
- Université de Paris, Centre National de la Recherche Scientifique, Institut Jacques Monod, Paris, France
| | - Marc de la Roche
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Paul T Conduit
- Department of Zoology, University of Cambridge, Cambridge, UK.,Université de Paris, Centre National de la Recherche Scientifique, Institut Jacques Monod, Paris, France
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17
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Brilot AF, Lyon AS, Zelter A, Viswanath S, Maxwell A, MacCoss MJ, Muller EG, Sali A, Davis TN, Agard DA. CM1-driven assembly and activation of yeast γ-tubulin small complex underlies microtubule nucleation. eLife 2021; 10:e65168. [PMID: 33949948 PMCID: PMC8099430 DOI: 10.7554/elife.65168] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 04/12/2021] [Indexed: 01/08/2023] Open
Abstract
Microtubule (MT) nucleation is regulated by the γ-tubulin ring complex (γTuRC), conserved from yeast to humans. In Saccharomyces cerevisiae, γTuRC is composed of seven identical γ-tubulin small complex (γTuSC) sub-assemblies, which associate helically to template MT growth. γTuRC assembly provides a key point of regulation for the MT cytoskeleton. Here, we combine crosslinking mass spectrometry, X-ray crystallography, and cryo-EM structures of both monomeric and dimeric γTuSCs, and open and closed helical γTuRC assemblies in complex with Spc110p to elucidate the mechanisms of γTuRC assembly. γTuRC assembly is substantially aided by the evolutionarily conserved CM1 motif in Spc110p spanning a pair of adjacent γTuSCs. By providing the highest resolution and most complete views of any γTuSC assembly, our structures allow phosphorylation sites to be mapped, surprisingly suggesting that they are mostly inhibitory. A comparison of our structures with the CM1 binding site in the human γTuRC structure at the interface between GCP2 and GCP6 allows for the interpretation of significant structural changes arising from CM1 helix binding to metazoan γTuRC.
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Affiliation(s)
- Axel F Brilot
- Department of Biochemistry and Biophysics, University of California at San FranciscoSan FranciscoUnited States
| | - Andrew S Lyon
- Department of Biochemistry and Biophysics, University of California at San FranciscoSan FranciscoUnited States
| | - Alex Zelter
- Department of Biochemistry, University of WashingtonSeattleUnited States
| | - Shruthi Viswanath
- Department of Bioengineering and Therapeutic Sciences, University of California at San FranciscoSan FranciscoUnited States
| | - Alison Maxwell
- Department of Biochemistry and Biophysics, University of California at San FranciscoSan FranciscoUnited States
| | - Michael J MacCoss
- Department of Genome Sciences, University of WashingtonSeattleUnited States
| | - Eric G Muller
- Department of Biochemistry, University of WashingtonSeattleUnited States
| | - Andrej Sali
- Department of Bioengineering and Therapeutic Sciences, University of California at San FranciscoSan FranciscoUnited States
| | - Trisha N Davis
- Department of Biochemistry, University of WashingtonSeattleUnited States
| | - David A Agard
- Department of Biochemistry and Biophysics, University of California at San FranciscoSan FranciscoUnited States
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18
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Vasquez-Limeta A, Loncarek J. Human centrosome organization and function in interphase and mitosis. Semin Cell Dev Biol 2021; 117:30-41. [PMID: 33836946 DOI: 10.1016/j.semcdb.2021.03.020] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 03/26/2021] [Accepted: 03/28/2021] [Indexed: 01/15/2023]
Abstract
Centrosomes were first described by Edouard Van Beneden and named and linked to chromosome segregation by Theodor Boveri around 1870. In the 1960-1980s, electron microscopy studies have revealed the remarkable ultrastructure of a centriole -- a nine-fold symmetrical microtubular assembly that resides within a centrosome and organizes it. Less than two decades ago, proteomics and genomic screens conducted in multiple species identified hundreds of centriole and centrosome core proteins and revealed the evolutionarily conserved nature of the centriole assembly pathway. And now, super resolution microscopy approaches and improvements in cryo-tomography are bringing an unparalleled nanoscale-detailed picture of the centriole and centrosome architecture. In this chapter, we summarize the current knowledge about the architecture of human centrioles. We discuss the structured organization of centrosome components in interphase, focusing on localization/function relationship. We discuss the process of centrosome maturation and mitotic spindle pole assembly in centriolar and acentriolar cells, emphasizing recent literature.
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Affiliation(s)
| | - Jadranka Loncarek
- Laboratory of Protein Dynamics and Signaling, NIH/NCI, Frederick 21702, MD, USA.
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19
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Chumová J, Kourová H, Trögelová L, Daniel G, Binarová P. γ-Tubulin Complexes and Fibrillar Arrays: Two Conserved High Molecular Forms with Many Cellular Functions. Cells 2021; 10:cells10040776. [PMID: 33915825 PMCID: PMC8066788 DOI: 10.3390/cells10040776] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 03/29/2021] [Accepted: 03/30/2021] [Indexed: 11/29/2022] Open
Abstract
Higher plants represent a large group of eukaryotes where centrosomes are absent. The functions of γ-tubulin small complexes (γ-TuSCs) and γ-tubulin ring complexes (γ-TuRCs) in metazoans and fungi in microtubule nucleation are well established and the majority of components found in the complexes are present in plants. However, plant microtubules are also nucleated in a γ-tubulin-dependent but γ-TuRC-independent manner. There is growing evidence that γ-tubulin is a microtubule nucleator without being complexed in γ-TuRC. Fibrillar arrays of γ-tubulin were demonstrated in plant and animal cells and the ability of γ-tubulin to assemble into linear oligomers/polymers was confirmed in vitro for both native and recombinant γ-tubulin. The functions of γ-tubulin as a template for microtubule nucleation or in promoting spontaneous nucleation is outlined. Higher plants represent an excellent model for studies on the role of γ-tubulin in nucleation due to their acentrosomal nature and high abundancy and conservation of γ-tubulin including its intrinsic ability to assemble filaments. The defining scaffolding or sequestration functions of plant γ-tubulin in microtubule organization or in nuclear processes will help our understanding of its cellular roles in eukaryotes.
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Affiliation(s)
- Jana Chumová
- Institute of Microbiology of the Czech Academy of Sciences, Vídeňská1083, 142 20 Prague, Czech Republic; (J.C.); (H.K.); (L.T.)
| | - Hana Kourová
- Institute of Microbiology of the Czech Academy of Sciences, Vídeňská1083, 142 20 Prague, Czech Republic; (J.C.); (H.K.); (L.T.)
| | - Lucie Trögelová
- Institute of Microbiology of the Czech Academy of Sciences, Vídeňská1083, 142 20 Prague, Czech Republic; (J.C.); (H.K.); (L.T.)
| | - Geoffrey Daniel
- Department of Biomaterials and Technology/Wood Science, Swedish University of Agricultural Sciences, 750-07 Uppsala, Sweden;
| | - Pavla Binarová
- Institute of Microbiology of the Czech Academy of Sciences, Vídeňská1083, 142 20 Prague, Czech Republic; (J.C.); (H.K.); (L.T.)
- Correspondence: ; Tel.: +420-241-062-130
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20
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Jaiswal S, Kasera H, Jain S, Khandelwal S, Singh P. Centrosome: A Microtubule Nucleating Cellular Machinery. J Indian Inst Sci 2021. [DOI: 10.1007/s41745-020-00213-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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21
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Ohta M, Zhao Z, Wu D, Wang S, Harrison JL, Gómez-Cavazos JS, Desai A, Oegema KF. Polo-like kinase 1 independently controls microtubule-nucleating capacity and size of the centrosome. J Cell Biol 2021; 220:211652. [PMID: 33399854 PMCID: PMC7788462 DOI: 10.1083/jcb.202009083] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 11/14/2020] [Accepted: 11/20/2020] [Indexed: 12/18/2022] Open
Abstract
Centrosomes are composed of a centriolar core surrounded by a pericentriolar material (PCM) matrix that docks microtubule-nucleating γ-tubulin complexes. During mitotic entry, the PCM matrix increases in size and nucleating capacity in a process called centrosome maturation. Polo-like kinase 1 (PLK1) is recruited to centrosomes and phosphorylates PCM matrix proteins to drive their self-assembly, which leads to PCM expansion. Here, we show that in addition to controlling PCM expansion, PLK1 independently controls the generation of binding sites for γ-tubulin complexes on the PCM matrix. Selectively preventing the generation of PLK1-dependent γ-tubulin docking sites led to spindle defects and impaired chromosome segregation without affecting PCM expansion, highlighting the importance of phospho-regulated centrosomal γ-tubulin docking sites in spindle assembly. Inhibiting both γ-tubulin docking and PCM expansion by mutating substrate target sites recapitulated the effects of loss of centrosomal PLK1 on the ability of centrosomes to catalyze spindle assembly.
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Affiliation(s)
- Midori Ohta
- Ludwig Institute for Cancer Research, La Jolla, CA,Midori Ohta:
| | - Zhiling Zhao
- Ludwig Institute for Cancer Research, La Jolla, CA
| | - Di Wu
- Ludwig Institute for Cancer Research, La Jolla, CA
| | - Shaohe Wang
- Ludwig Institute for Cancer Research, La Jolla, CA
| | - Jennifer L. Harrison
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA
| | - J. Sebastián Gómez-Cavazos
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA
| | - Arshad Desai
- Ludwig Institute for Cancer Research, La Jolla, CA,Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA,Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA
| | - Karen F. Oegema
- Ludwig Institute for Cancer Research, La Jolla, CA,Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA,Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA,Correspondence to Karen Oegema:
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22
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Kuriyama R, Fisher CR. A novel mitosis-specific Cep215 domain interacts with Cep192 and phosphorylated Aurora A for organization of spindle poles. J Cell Sci 2020; 133:133/24/jcs240267. [PMID: 33376154 DOI: 10.1242/jcs.240267] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 10/29/2020] [Indexed: 11/20/2022] Open
Abstract
The centrosome, which consists of centrioles and pericentriolar material (PCM), becomes mature and assembles mitotic spindles by increasing the number of microtubules (MTs) emanating from the PCM. Among the molecules involved in centrosome maturation, Cep192 and Aurora A (AurA, also known as AURKA) are primarily responsible for recruitment of γ-tubulin and MT nucleators, whereas pericentrin (PCNT) is required for PCM organization. However, the role of Cep215 (also known as CDK5RAP2) in centrosome maturation remains elusive. Cep215 possesses binding domains for γ-tubulin, PCNT and MT motors that transport acentrosomal MTs towards the centrosome. We identify a mitosis-specific centrosome-targeting domain of Cep215 (215N) that interacts with Cep192 and phosphorylated AurA (pAurA). Cep192 is essential for targeting 215N to centrosomes, and centrosomal localization of 215N and pAurA is mutually dependent. Cep215 has a relatively minor role in γ-tubulin recruitment to the mitotic centrosome. However, it has been shown previously that this protein is important for connecting mitotic centrosomes to spindle poles. Based on the results of rescue experiments using versions of Cep215 with different domain deletions, we conclude that Cep215 plays a role in maintaining the structural integrity of the spindle pole by providing a platform for the molecules involved in centrosome maturation.
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Affiliation(s)
- Ryoko Kuriyama
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Cody R Fisher
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA
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23
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Watanabe S, Meitinger F, Shiau AK, Oegema K, Desai A. Centriole-independent mitotic spindle assembly relies on the PCNT-CDK5RAP2 pericentriolar matrix. J Cell Biol 2020; 219:e202006010. [PMID: 33170211 PMCID: PMC7658699 DOI: 10.1083/jcb.202006010] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 09/27/2020] [Accepted: 10/06/2020] [Indexed: 01/04/2023] Open
Abstract
Centrosomes, composed of centrioles that recruit a pericentriolar material (PCM) matrix assembled from PCNT and CDK5RAP2, catalyze mitotic spindle assembly. Here, we inhibit centriole formation and/or remove PCNT-CDK5RAP2 in RPE1 cells to address their relative contributions to spindle formation. While CDK5RAP2 and PCNT are normally dispensable for spindle formation, they become essential when centrioles are absent. Acentriolar spindle assembly is accompanied by the formation of foci containing PCNT and CDK5RAP2 via a microtubule and Polo-like kinase 1-dependent process. Foci formation and spindle assembly require PCNT-CDK5RAP2-dependent matrix assembly and the ability of CDK5RAP2 to recruit γ-tubulin complexes. Thus, the PCM matrix can self-organize independently of centrioles to generate microtubules for spindle assembly; conversely, an alternative centriole-anchored mechanism supports spindle assembly when the PCM matrix is absent. Extension to three cancer cell lines revealed similar results in HeLa cells, whereas DLD1 and U2OS cells could assemble spindles in the absence of centrioles and PCNT-CDK5RAP2, suggesting cell type variation in spindle assembly mechanisms.
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Affiliation(s)
- Sadanori Watanabe
- Ludwig Institute for Cancer Research, La Jolla, CA
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Franz Meitinger
- Ludwig Institute for Cancer Research, La Jolla, CA
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA
| | - Andrew K. Shiau
- Ludwig Institute for Cancer Research, La Jolla, CA
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA
- Small Molecule Discovery Program, Ludwig Institute for Cancer Research, La Jolla, CA
| | - Karen Oegema
- Ludwig Institute for Cancer Research, La Jolla, CA
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA
| | - Arshad Desai
- Ludwig Institute for Cancer Research, La Jolla, CA
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA
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24
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Principal Postulates of Centrosomal Biology. Version 2020. Cells 2020; 9:cells9102156. [PMID: 32987651 PMCID: PMC7598677 DOI: 10.3390/cells9102156] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 09/10/2020] [Accepted: 09/21/2020] [Indexed: 12/13/2022] Open
Abstract
The centrosome, which consists of two centrioles surrounded by pericentriolar material, is a unique structure that has retained its main features in organisms of various taxonomic groups from unicellular algae to mammals over one billion years of evolution. In addition to the most noticeable function of organizing the microtubule system in mitosis and interphase, the centrosome performs many other cell functions. In particular, centrioles are the basis for the formation of sensitive primary cilia and motile cilia and flagella. Another principal function of centrosomes is the concentration in one place of regulatory proteins responsible for the cell's progression along the cell cycle. Despite the existing exceptions, the functioning of the centrosome is subject to general principles, which are discussed in this review.
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25
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Leong SL, Lynch EM, Zou J, Tay YD, Borek WE, Tuijtel MW, Rappsilber J, Sawin KE. Reconstitution of Microtubule Nucleation In Vitro Reveals Novel Roles for Mzt1. Curr Biol 2019; 29:2199-2207.e10. [PMID: 31287970 PMCID: PMC6616311 DOI: 10.1016/j.cub.2019.05.058] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 04/29/2019] [Accepted: 05/23/2019] [Indexed: 12/25/2022]
Abstract
Microtubule (MT) nucleation depends on the γ-tubulin complex (γ-TuC), in which multiple copies of the heterotetrameric γ-tubulin small complex (γ-TuSC) associate to form a ring-like structure (in metazoans, γ-tubulin ring complex; γ-TuRC) [1-7]. Additional conserved regulators of the γ-TuC include the small protein Mzt1 (MOZART1 in human; GIP1/1B and GIP2/1A in plants) [8-13] and proteins containing a Centrosomin Motif 1 (CM1) domain [10, 14-19]. Many insights into γ-TuC regulators have come from in vivo analysis in fission yeast Schizosaccharomyces pombe. The S. pombe CM1 protein Mto1 recruits the γ-TuC to microtubule-organizing centers (MTOCs) [14, 20-22], and analysis of Mto1[bonsai], a truncated version of Mto1 that cannot localize to MTOCs, has shown that Mto1 also has a role in γ-TuC activation [23]. S. pombe Mzt1 interacts with γ-TuSC and is essential for γ-TuC function and localization to MTOCs [11, 12]. However, the mechanisms by which Mzt1 functions remain unclear. Here we describe reconstitution of MT nucleation using purified recombinant Mto1[bonsai], the Mto1 partner protein Mto2, γ-TuSC, and Mzt1. Multiple copies of the six proteins involved coassemble to form a 34-40S ring-like "MGM" holocomplex that is a potent MT nucleator in vitro. Using purified MGM and subcomplexes, we investigate the role of Mzt1 in MT nucleation. Our results suggest that Mzt1 is critical to stabilize Alp6, the S. pombe homolog of human γ-TuSC protein GCP3, in an "interaction-competent" form within the γ-TuSC. This is essential for MGM to become a functional nucleator.
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Affiliation(s)
- Su Ling Leong
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Eric M Lynch
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Juan Zou
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Ye Dee Tay
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Weronika E Borek
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Maarten W Tuijtel
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Juri Rappsilber
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK; Chair of Bioanalytics, Institute of Biotechnology, Technische Universität Berlin, Berlin 13355, Germany
| | - Kenneth E Sawin
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK.
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26
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Abstract
Microtubules are major constituents of the cytoskeleton in all eukaryotic cells. They are essential for chromosome segregation during cell division, for directional intracellular transport and for building specialized cellular structures such as cilia or flagella. Their assembly has to be controlled spatially and temporally. For this, the cell uses multiprotein complexes containing γ-tubulin. γ-Tubulin has been found in two different types of complexes, γ-tubulin small complexes and γ-tubulin ring complexes. Binding to adaptors and activator proteins transforms these complexes into structural templates that drive the nucleation of new microtubules in a highly controlled manner. This review discusses recent advances on the mechanisms of assembly, recruitment and activation of γ-tubulin complexes at microtubule-organizing centres.
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Affiliation(s)
- Dorian Farache
- Centre de Biologie Intégrative, Centre de Biologie du Développement, CNRS-Université Toulouse III, 31062 Toulouse, France
| | - Laurent Emorine
- Centre de Biologie Intégrative, Centre de Biologie du Développement, CNRS-Université Toulouse III, 31062 Toulouse, France
| | - Laurence Haren
- Centre de Biologie Intégrative, Centre de Biologie du Développement, CNRS-Université Toulouse III, 31062 Toulouse, France
| | - Andreas Merdes
- Centre de Biologie Intégrative, Centre de Biologie du Développement, CNRS-Université Toulouse III, 31062 Toulouse, France
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27
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Pham TT, Monnard A, Helenius J, Lund E, Lee N, Müller DJ, Cabernard C. Spatiotemporally Controlled Myosin Relocalization and Internal Pressure Generate Sibling Cell Size Asymmetry. iScience 2019; 13:9-19. [PMID: 30785031 PMCID: PMC6383127 DOI: 10.1016/j.isci.2019.02.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 11/12/2018] [Accepted: 01/30/2019] [Indexed: 11/24/2022] Open
Abstract
Metazoan cells can generate unequal-sized sibling cells during cell division. This form of asymmetric cell division depends on spindle geometry and Myosin distribution, but the underlying mechanics are unclear. Here, we use atomic force microscopy and live cell imaging to elucidate the biophysical forces involved in the establishment of physical asymmetry in Drosophila neural stem cells. We show that initial apical cortical expansion is driven by hydrostatic pressure, peaking shortly after anaphase onset, and enabled by a relief of actomyosin contractile tension on the apical cell cortex. An increase in contractile tension at the cleavage furrow combined with the relocalization of basally located Myosin initiates basal and sustains apical extension. We propose that spatiotemporally controlled actomyosin contractile tension and hydrostatic pressure enable biased cortical expansion to generate sibling cell size asymmetry. However, dynamic cleavage furrow repositioning can compensate for the lack of biased expansion to establish physical asymmetry.
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Affiliation(s)
- Tri Thanh Pham
- Department of Biology, University of Washington, Life Science Building, Seattle, WA 98195, USA
| | - Arnaud Monnard
- Department of Biology, University of Washington, Life Science Building, Seattle, WA 98195, USA; Biozentrum, University of Basel, Klingelbergstrasse 50-70, 4056 Basel, Switzerland
| | - Jonne Helenius
- Eidgenössische Technische Hochschule (ETH) Zurich, Department of Biosystems Science and Engineering, Mattenstrasse 26, 4058 Basel, Switzerland
| | - Erik Lund
- Department of Biology, University of Washington, Life Science Building, Seattle, WA 98195, USA
| | - Nicole Lee
- Department of Biology, University of Washington, Life Science Building, Seattle, WA 98195, USA; Cancer Science Institute, National University of Singapore, 14 Medical Dr., Singapore 117599, Singapore
| | - Daniel J Müller
- Eidgenössische Technische Hochschule (ETH) Zurich, Department of Biosystems Science and Engineering, Mattenstrasse 26, 4058 Basel, Switzerland
| | - Clemens Cabernard
- Department of Biology, University of Washington, Life Science Building, Seattle, WA 98195, USA.
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28
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Magnaghi-Jaulin L, Eot-Houllier G, Gallaud E, Giet R. Aurora A Protein Kinase: To the Centrosome and Beyond. Biomolecules 2019; 9:biom9010028. [PMID: 30650622 PMCID: PMC6359016 DOI: 10.3390/biom9010028] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 01/09/2019] [Accepted: 01/09/2019] [Indexed: 12/25/2022] Open
Abstract
Accurate chromosome segregation requires the perfect spatiotemporal rearrangement of the cellular cytoskeleton. Isolated more than two decades ago from Drosophila, Aurora A is a widespread protein kinase that plays key roles during cell division. Numerous studies have described the localisation of Aurora A at centrosomes, the mitotic spindle, and, more recently, at mitotic centromeres. In this review, we will summarise the cytoskeletal rearrangements regulated by Aurora A during cell division. We will also discuss the recent discoveries showing that Aurora A also controls not only the dynamics of the cortical proteins but also regulates the centromeric proteins, revealing new roles for this kinase during cell division.
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Affiliation(s)
- Laura Magnaghi-Jaulin
- University of Rennes, CNRS UMR 6290, IGDR-Institute of Genetics and Development of Rennes, F-35000 Rennes, France.
| | - Grégory Eot-Houllier
- University of Rennes, CNRS UMR 6290, IGDR-Institute of Genetics and Development of Rennes, F-35000 Rennes, France.
| | - Emmanuel Gallaud
- University of Rennes, CNRS UMR 6290, IGDR-Institute of Genetics and Development of Rennes, F-35000 Rennes, France.
| | - Régis Giet
- University of Rennes, CNRS UMR 6290, IGDR-Institute of Genetics and Development of Rennes, F-35000 Rennes, France.
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29
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Blake-Hedges C, Megraw TL. Coordination of Embryogenesis by the Centrosome in Drosophila melanogaster. Results Probl Cell Differ 2019; 67:277-321. [PMID: 31435800 DOI: 10.1007/978-3-030-23173-6_12] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The first 3 h of Drosophila melanogaster embryo development are exemplified by rapid nuclear divisions within a large syncytium, transforming the zygote to the cellular blastoderm after 13 successive cleavage divisions. As the syncytial embryo develops, it relies on centrosomes and cytoskeletal dynamics to transport nuclei, maintain uniform nuclear distribution throughout cleavage cycles, ensure generation of germ cells, and coordinate cellularization. For the sake of this review, we classify six early embryo stages that rely on processes coordinated by the centrosome and its regulation of the cytoskeleton. The first stage features migration of one of the female pronuclei toward the male pronucleus following maturation of the first embryonic centrosomes. Two subsequent stages distribute the nuclei first axially and then radially in the embryo. The remaining three stages involve centrosome-actin dynamics that control cortical plasma membrane morphogenesis. In this review, we highlight the dynamics of the centrosome and its role in controlling the six stages that culminate in the cellularization of the blastoderm embryo.
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Affiliation(s)
- Caitlyn Blake-Hedges
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL, USA.
| | - Timothy L Megraw
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL, USA
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30
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Bridging centrioles and PCM in proper space and time. Essays Biochem 2018; 62:793-801. [PMID: 30429283 PMCID: PMC6281471 DOI: 10.1042/ebc20180036] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 10/08/2018] [Accepted: 10/22/2018] [Indexed: 01/15/2023]
Abstract
Throughout biology, specifying cellular events at the correct location and time is necessary for ensuring proper function. The formation of robust microtubule organizing centers (MTOCs) in mitosis is one such event that must be restricted in space to centrosomes to prevent ectopic MTOC formation elsewhere in the cell, a situation that can result in multipolar spindle formation and aneuploidy. The process of reaching maximum centrosome MTOC activity in late G2, known as centrosome maturation, ensures accurate timing of nuclear envelope breakdown and proper chromosome attachment. Although centrosome maturation has been recognized for over a century, the spatial and temporal regulatory mechanisms that direct MTOC activation are poorly understood. Here, we review Sas-4/CPAP, Asterless/Cep152, Spd-2/Cep192, and PLP/Pericentrin, a group of proteins we refer to as 'bridge' proteins that reside at the surface of centrioles, perfectly positioned to serve as the gatekeepers of proper centrosome maturation at the perfect place and time.
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31
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Microtubule nucleation by γ-tubulin complexes and beyond. Essays Biochem 2018; 62:765-780. [PMID: 30315097 PMCID: PMC6281477 DOI: 10.1042/ebc20180028] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2018] [Revised: 09/05/2018] [Accepted: 09/13/2018] [Indexed: 12/21/2022]
Abstract
In this short review, we give an overview of microtubule nucleation within cells. It is nearly 30 years since the discovery of γ-tubulin, a member of the tubulin superfamily essential for proper microtubule nucleation in all eukaryotes. γ-tubulin associates with other proteins to form multiprotein γ-tubulin ring complexes (γ-TuRCs) that template and catalyse the otherwise kinetically unfavourable assembly of microtubule filaments. These filaments can be dynamic or stable and they perform diverse functions, such as chromosome separation during mitosis and intracellular transport in neurons. The field has come a long way in understanding γ-TuRC biology but several important and unanswered questions remain, and we are still far from understanding the regulation of microtubule nucleation in a multicellular context. Here, we review the current literature on γ-TuRC assembly, recruitment, and activation and discuss the potential importance of γ-TuRC heterogeneity, the role of non-γ-TuRC proteins in microtubule nucleation, and whether γ-TuRCs could serve as good drug targets for cancer therapy.
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32
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Tillery MML, Blake-Hedges C, Zheng Y, Buchwalter RA, Megraw TL. Centrosomal and Non-Centrosomal Microtubule-Organizing Centers (MTOCs) in Drosophila melanogaster. Cells 2018; 7:E121. [PMID: 30154378 PMCID: PMC6162459 DOI: 10.3390/cells7090121] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 08/19/2018] [Accepted: 08/20/2018] [Indexed: 12/14/2022] Open
Abstract
The centrosome is the best-understood microtubule-organizing center (MTOC) and is essential in particular cell types and at specific stages during Drosophila development. The centrosome is not required zygotically for mitosis or to achieve full animal development. Nevertheless, centrosomes are essential maternally during cleavage cycles in the early embryo, for male meiotic divisions, for efficient division of epithelial cells in the imaginal wing disc, and for cilium/flagellum assembly in sensory neurons and spermatozoa. Importantly, asymmetric and polarized division of stem cells is regulated by centrosomes and by the asymmetric regulation of their microtubule (MT) assembly activity. More recently, the components and functions of a variety of non-centrosomal microtubule-organizing centers (ncMTOCs) have begun to be elucidated. Throughout Drosophila development, a wide variety of unique ncMTOCs form in epithelial and non-epithelial cell types at an assortment of subcellular locations. Some of these cell types also utilize the centrosomal MTOC, while others rely exclusively on ncMTOCs. The impressive variety of ncMTOCs being discovered provides novel insight into the diverse functions of MTOCs in cells and tissues. This review highlights our current knowledge of the composition, assembly, and functional roles of centrosomal and non-centrosomal MTOCs in Drosophila.
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Affiliation(s)
- Marisa M L Tillery
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| | - Caitlyn Blake-Hedges
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| | - Yiming Zheng
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| | - Rebecca A Buchwalter
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
| | - Timothy L Megraw
- Department of Biomedical Sciences, Florida State University, 1115 West Call St., Tallahassee, FL 32306, USA.
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33
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Tovey CA, Tubman CE, Hamrud E, Zhu Z, Dyas AE, Butterfield AN, Fyfe A, Johnson E, Conduit PT. γ-TuRC Heterogeneity Revealed by Analysis of Mozart1. Curr Biol 2018; 28:2314-2323.e6. [PMID: 29983314 PMCID: PMC6065531 DOI: 10.1016/j.cub.2018.05.044] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 04/06/2018] [Accepted: 05/16/2018] [Indexed: 12/13/2022]
Abstract
Microtubules are essential for various cell processes [1] and are nucleated by multi-protein γ-tubulin ring complexes (γ-TuRCs) at various microtubule organizing centers (MTOCs), including centrosomes [2-6]. Recruitment of γ-TuRCs to different MTOCs at different times influences microtubule array formation, but how this is regulated remains an open question. It also remains unclear whether all γ-TuRCs within the same organism have the same composition and how any potential heterogeneity might influence γ-TuRC recruitment. MOZART1 (Mzt1) was recently identified as a γ-TuRC component [7, 8] and is conserved in nearly all eukaryotes [6, 9]. Mzt1 has so far been studied in cultured human cells, yeast, and plants; its absence leads to failures in γ-TuRC recruitment and cell division, resulting in cell death [7, 9-15]. Mzt1 is small (∼8.5 kDa), binds directly to core γ-TuRC components [9, 10, 14, 15], and appears to mediate the interaction between γ-TuRCs and proteins that tether γ-TuRCs to MTOCs [9, 15]. Here, we use Drosophila to investigate the function of Mzt1 in a multicellular animal for the first time. Surprisingly, we find that Drosophila Mzt1 is expressed only in the testes and is present in γ-TuRCs recruited to basal bodies, but not to mitochondria, in developing sperm cells. mzt1 mutants are viable but have defects in basal body positioning and γ-TuRC recruitment to centriole adjuncts; sperm formation is affected and mutants display a rapid age-dependent decline in sperm motility and male fertility. Our results reveal that tissue-specific and MTOC-specific γ-TuRC heterogeneity exist in Drosophila and highlight the complexity of γ-TuRC recruitment in a multicellular animal.
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Affiliation(s)
- Corinne A Tovey
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Chloe E Tubman
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Eva Hamrud
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Zihan Zhu
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Anna E Dyas
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Andrew N Butterfield
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Alex Fyfe
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Errin Johnson
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Paul T Conduit
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
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34
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Bao XX, Spanos C, Kojidani T, Lynch EM, Rappsilber J, Hiraoka Y, Haraguchi T, Sawin KE. Exportin Crm1 is repurposed as a docking protein to generate microtubule organizing centers at the nuclear pore. eLife 2018; 7:e33465. [PMID: 29809148 PMCID: PMC6008054 DOI: 10.7554/elife.33465] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 05/21/2018] [Indexed: 01/04/2023] Open
Abstract
Non-centrosomal microtubule organizing centers (MTOCs) are important for microtubule organization in many cell types. In fission yeast Schizosaccharomyces pombe, the protein Mto1, together with partner protein Mto2 (Mto1/2 complex), recruits the γ-tubulin complex to multiple non-centrosomal MTOCs, including the nuclear envelope (NE). Here, we develop a comparative-interactome mass spectrometry approach to determine how Mto1 localizes to the NE. Surprisingly, we find that Mto1, a constitutively cytoplasmic protein, docks at nuclear pore complexes (NPCs), via interaction with exportin Crm1 and cytoplasmic FG-nucleoporin Nup146. Although Mto1 is not a nuclear export cargo, it binds Crm1 via a nuclear export signal-like sequence, and docking requires both Ran in the GTP-bound state and Nup146 FG repeats. In addition to determining the mechanism of MTOC formation at the NE, our results reveal a novel role for Crm1 and the nuclear export machinery in the stable docking of a cytoplasmic protein complex at NPCs.
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Affiliation(s)
- Xun X Bao
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Christos Spanos
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Tomoko Kojidani
- Advanced ICT Research Institute KobeNational Institute of Information and Communications TechnologyKobeJapan
- Department of Chemical and Biological Sciences, Faculty of ScienceJapan Women’s UniversityTokyoJapan
| | - Eric M Lynch
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Juri Rappsilber
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
- Department of BioanalyticsInstitute of Biotechnology, Technische Universität BerlinBerlinGermany
| | - Yasushi Hiraoka
- Advanced ICT Research Institute KobeNational Institute of Information and Communications TechnologyKobeJapan
- Graduate School of Frontier BiosciencesOsaka UniversitySuitaJapan
| | - Tokuko Haraguchi
- Advanced ICT Research Institute KobeNational Institute of Information and Communications TechnologyKobeJapan
- Graduate School of Frontier BiosciencesOsaka UniversitySuitaJapan
| | - Kenneth E Sawin
- Wellcome Centre for Cell Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
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35
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Citron YR, Fagerstrom CJ, Keszthelyi B, Huang B, Rusan NM, Kelly MJS, Agard DA. The centrosomin CM2 domain is a multi-functional binding domain with distinct cell cycle roles. PLoS One 2018; 13:e0190530. [PMID: 29315319 PMCID: PMC5760045 DOI: 10.1371/journal.pone.0190530] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 12/15/2017] [Indexed: 11/18/2022] Open
Abstract
The centrosome serves as the main microtubule-organizing center in metazoan cells, yet despite its functional importance, little is known mechanistically about the structure and organizational principles that dictate protein organization in the centrosome. In particular, the protein-protein interactions that allow for the massive structural transition between the tightly organized interphase centrosome and the highly expanded matrix-like arrangement of the mitotic centrosome have been largely uncharacterized. Among the proteins that undergo a major transition is the Drosophila melanogaster protein centrosomin that contains a conserved carboxyl terminus motif, CM2. Recent crystal structures have shown this motif to be dimeric and capable of forming an intramolecular interaction with a central region of centrosomin. Here we use a combination of in-cell microscopy and in vitro oligomer assessment to show that dimerization is not necessary for CM2 recruitment to the centrosome and that CM2 alone undergoes significant cell cycle dependent rearrangement. We use NMR binding assays to confirm this intramolecular interaction and show that residues involved in solution are consistent with the published crystal structure and identify L1137 as critical for binding. Additionally, we show for the first time an in vitro interaction of CM2 with the Drosophila pericentrin-like-protein that exploits the same set of residues as the intramolecular interaction. Furthermore, NMR experiments reveal a calcium sensitive interaction between CM2 and calmodulin. Although unexpected because of sequence divergence, this suggests that centrosomin-mediated assemblies, like the mammalian pericentrin, may be calcium regulated. From these results, we suggest an expanded model where during interphase CM2 interacts with pericentrin-like-protein to form a layer of centrosomin around the centriole wall and that at the onset of mitosis this population acts as a nucleation site of intramolecular centrosomin interactions that support the expansion into the metaphase matrix.
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Affiliation(s)
- Y. Rose Citron
- Department of Biochemistry and Biophysics and the Howard Hughes Medical Institute, University of California San Francisco, San Francisco, California, United States of America
| | - Carey J. Fagerstrom
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Bettina Keszthelyi
- Department of Biochemistry and Biophysics and the Howard Hughes Medical Institute, University of California San Francisco, San Francisco, California, United States of America
| | - Bo Huang
- Department of Pharmaceutical Chemistry and Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, United States of America
| | - Nasser M. Rusan
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Mark J. S. Kelly
- Department of Pharmaceutical Chemistry and Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, United States of America
| | - David A. Agard
- Department of Biochemistry and Biophysics and the Howard Hughes Medical Institute, University of California San Francisco, San Francisco, California, United States of America
- * E-mail:
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36
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Lerit DA, Shebelut CW, Lawlor KJ, Rusan NM, Gavis ER, Schedl P, Deshpande G. Germ Cell-less Promotes Centrosome Segregation to Induce Germ Cell Formation. Cell Rep 2017; 18:831-839. [PMID: 28122234 DOI: 10.1016/j.celrep.2016.12.074] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 11/22/2016] [Accepted: 12/22/2016] [Indexed: 11/12/2022] Open
Abstract
The primordial germ cells (PGCs) specified during embryogenesis serve as progenitors to the adult germline stem cells. In Drosophila, the proper specification and formation of PGCs require both centrosomes and germ plasm, which contains the germline determinants. Centrosomes are microtubule (MT)-organizing centers that ensure the faithful segregation of germ plasm into PGCs. To date, mechanisms that modulate centrosome behavior to engineer PGC development have remained elusive. Only one germ plasm component, Germ cell-less (Gcl), is known to play a role in PGC formation. Here, we show that Gcl engineers PGC formation by regulating centrosome dynamics. Loss of gcl leads to aberrant centrosome separation and elaboration of the astral MT network, resulting in inefficient germ plasm segregation and aborted PGC cellularization. Importantly, compromising centrosome separation alone is sufficient to mimic the gcl loss-of-function phenotypes. We conclude Gcl functions as a key regulator of centrosome separation required for proper PGC development.
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Affiliation(s)
- Dorothy A Lerit
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.
| | - Conrad W Shebelut
- School of Medicine, University of Virginia, Charlottesville, VA 22908, USA
| | - Kristen J Lawlor
- Department of Neuroscience, Columbia University, New York, NY 10032, USA
| | - Nasser M Rusan
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Elizabeth R Gavis
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Paul Schedl
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA; Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, Moscow 119991, Russia
| | - Girish Deshpande
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
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37
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Bosveld F, Ainslie A, Bellaïche Y. Sequential activities of Dynein, Mud and Asp in centrosome-spindle coupling maintain centrosome number upon mitosis. J Cell Sci 2017; 130:3557-3567. [PMID: 28864767 DOI: 10.1242/jcs.201350] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 07/31/2017] [Indexed: 12/15/2022] Open
Abstract
Centrosomes nucleate microtubules and are tightly coupled to the bipolar spindle to ensure genome integrity, cell division orientation and centrosome segregation. While the mechanisms of centrosome-dependent microtubule nucleation and bipolar spindle assembly have been the focus of numerous works, less is known about the mechanisms ensuring the centrosome-spindle coupling. The conserved NuMA protein (Mud in Drosophila) is best known for its role in spindle orientation. Here, we analyzed the role of Mud and two of its interactors, Asp and Dynein, in the regulation of centrosome numbers in Drosophila epithelial cells. We found that Dynein and Mud mainly initiate centrosome-spindle coupling prior to nuclear envelope breakdown (NEB) by promoting correct centrosome positioning or separation, while Asp acts largely independently of Dynein and Mud to maintain centrosome-spindle coupling. Failure in the centrosome-spindle coupling leads to mis-segregation of the two centrosomes into one daughter cell, resulting in cells with supernumerary centrosomes during subsequent divisions. Altogether, we propose that Dynein, Mud and Asp operate sequentially during the cell cycle to ensure efficient centrosome-spindle coupling in mitosis, thereby preventing centrosome mis-segregation to maintain centrosome number.
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Affiliation(s)
- Floris Bosveld
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, 75248 Paris, France .,Sorbonne Universités, UPMC Univ Paris 06, CNRS UMR 3215, INSERM U934, 75005 Paris, France
| | - Anna Ainslie
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, 75248 Paris, France.,Sorbonne Universités, UPMC Univ Paris 06, CNRS UMR 3215, INSERM U934, 75005 Paris, France
| | - Yohanns Bellaïche
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, 75248 Paris, France .,Sorbonne Universités, UPMC Univ Paris 06, CNRS UMR 3215, INSERM U934, 75005 Paris, France
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38
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Chen JV, Buchwalter RA, Kao LR, Megraw TL. A Splice Variant of Centrosomin Converts Mitochondria to Microtubule-Organizing Centers. Curr Biol 2017; 27:1928-1940.e6. [PMID: 28669756 DOI: 10.1016/j.cub.2017.05.090] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 05/02/2017] [Accepted: 05/31/2017] [Indexed: 11/25/2022]
Abstract
Non-centrosomal microtubule organizing centers (MTOCs) direct microtubule (MT) organization to exert diverse cell-type-specific functions. In Drosophila spermatids, the giant mitochondria provide structural platforms for MT reorganization to support elongation of the extremely long sperm. However, the molecular basis for this mitochondrial MTOC and other non-centrosomal MTOCs has not been discerned. Here we report that Drosophila centrosomin (cnn) expresses two major protein variants: the centrosomal form (CnnC) and a non-centrosomal form in testes (CnnT). CnnC is established as essential for functional centrosomes, the major MTOCs in animal cells. We show that CnnT is expressed exclusively in testes by alternative splicing and localizes to giant mitochondria in spermatids. In cell culture, CnnT targets to the mitochondrial surface, recruits the MT nucleator γ-tubulin ring complex (γ-TuRC), and is sufficient to convert mitochondria to MTOCs independent of core pericentriolar proteins that regulate MT assembly at centrosomes. We mapped two separate domains in CnnT: one that is necessary and sufficient to target it to mitochondria and another that is necessary and sufficient to recruit γ-TuRCs and nucleate MTs. In elongating spermatids, CnnT forms speckles on the giant mitochondria that are required to recruit γ-TuRCs to organize MTs and support spermiogenesis. This molecular characterization of the mitochondrial MTOC defines a minimal molecular requirement for MTOC generation and implicates the potent role of Cnn (or its related) proteins in the direct regulation of MT assembly and organization of non-centrosomal MTOCs.
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Affiliation(s)
- Jieyan V Chen
- Department of Biomedical Sciences, Florida State University, 1115 West Call Street, Tallahassee, FL 32306, USA.
| | - Rebecca A Buchwalter
- Department of Biomedical Sciences, Florida State University, 1115 West Call Street, Tallahassee, FL 32306, USA
| | - Ling-Rong Kao
- Department of Biomedical Sciences, Florida State University, 1115 West Call Street, Tallahassee, FL 32306, USA
| | - Timothy L Megraw
- Department of Biomedical Sciences, Florida State University, 1115 West Call Street, Tallahassee, FL 32306, USA.
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39
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Lattao R, Kovács L, Glover DM. The Centrioles, Centrosomes, Basal Bodies, and Cilia of Drosophila melanogaster. Genetics 2017; 206:33-53. [PMID: 28476861 PMCID: PMC5419478 DOI: 10.1534/genetics.116.198168] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 03/24/2017] [Indexed: 12/19/2022] Open
Abstract
Centrioles play a key role in the development of the fly. They are needed for the correct formation of centrosomes, the organelles at the poles of the spindle that can persist as microtubule organizing centers (MTOCs) into interphase. The ability to nucleate cytoplasmic microtubules (MTs) is a property of the surrounding pericentriolar material (PCM). The centriole has a dual life, existing not only as the core of the centrosome but also as the basal body, the structure that templates the formation of cilia and flagellae. Thus the structure and functions of the centriole, the centrosome, and the basal body have an impact upon many aspects of development and physiology that can readily be modeled in Drosophila Centrosomes are essential to give organization to the rapidly increasing numbers of nuclei in the syncytial embryo and for the spatially precise execution of cell division in numerous tissues, particularly during male meiosis. Although mitotic cell cycles can take place in the absence of centrosomes, this is an error-prone process that opens up the fly to developmental defects and the potential of tumor formation. Here, we review the structure and functions of the centriole, the centrosome, and the basal body in different tissues and cultured cells of Drosophila melanogaster, highlighting their contributions to different aspects of development and cell division.
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Affiliation(s)
- Ramona Lattao
- Department of Genetics, University of Cambridge, CB2 3EH, United Kingdom
| | - Levente Kovács
- Department of Genetics, University of Cambridge, CB2 3EH, United Kingdom
| | - David M Glover
- Department of Genetics, University of Cambridge, CB2 3EH, United Kingdom
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40
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Zheng Y, Mennella V, Marks S, Wildonger J, Elnagdi E, Agard D, Megraw TL. The Seckel syndrome and centrosomal protein Ninein localizes asymmetrically to stem cell centrosomes but is not required for normal development, behavior, or DNA damage response in Drosophila. Mol Biol Cell 2016; 27:1740-52. [PMID: 27053665 PMCID: PMC4884065 DOI: 10.1091/mbc.e15-09-0655] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 03/28/2016] [Indexed: 12/21/2022] Open
Abstract
Ninein associates with the microtubule regulator γ-tubulin, regulates microtubule assembly, and localizes to centrosomes and noncentrosomal microtubule-organizing centers in Drosophila. Ninein localizes to stem cell centrosomes asymmetrically, with a bias for the daughter centrosome. Remarkably, Ninein is dispensable for development, fertility, or viability. Ninein (Nin) is a centrosomal protein whose gene is mutated in Seckel syndrome (SCKL, MIM 210600), an inherited recessive disease that results in primordial dwarfism, cognitive deficiencies, and increased sensitivity to genotoxic stress. Nin regulates neural stem cell self-renewal, interkinetic nuclear migration, and microtubule assembly in mammals. Nin is evolutionarily conserved, yet its role in cell division and development has not been investigated in a model organism. Here we characterize the single Nin orthologue in Drosophila. Drosophila Nin localizes to the periphery of the centrosome but not at centriolar structures as in mammals. However, Nin shares the property of its mammalian orthologue of promoting microtubule assembly. In neural and germline stem cells, Nin localizes asymmetrically to the younger (daughter) centrosome, yet it is not required for the asymmetric division of stem cells. In wing epithelia and muscle, Nin localizes to noncentrosomal microtubule-organizing centers. Surprisingly, loss of nin expression from a nin mutant does not significantly affect embryonic and brain development, fertility, or locomotor performance of mutant flies or their survival upon exposure to DNA-damaging agents. Although it is not essential, our data suggest that Nin plays a supportive role in centrosomal and extracentrosomal microtubule organization and asymmetric stem cell division.
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Affiliation(s)
- Yiming Zheng
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL 32306-4300
| | - Vito Mennella
- Department of Biochemistry, University of Toronto, Toronto, M5G 0A4, Canada Cell Biology Program, The Hospital for Sick Children, Toronto, M5G 1X8, Canada
| | - Steven Marks
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL 32306-4300
| | - Jill Wildonger
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706
| | - Esraa Elnagdi
- Department of Biochemistry, University of Toronto, Toronto, M5G 0A4, Canada Cell Biology Program, The Hospital for Sick Children, Toronto, M5G 1X8, Canada
| | - David Agard
- The Howard Hughes Medical Institute and Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94143-2240
| | - Timothy L Megraw
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL 32306-4300
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41
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Chavali PL, Chandrasekaran G, Barr AR, Tátrai P, Taylor C, Papachristou EK, Woods CG, Chavali S, Gergely F. A CEP215-HSET complex links centrosomes with spindle poles and drives centrosome clustering in cancer. Nat Commun 2016; 7:11005. [PMID: 26987684 PMCID: PMC4802056 DOI: 10.1038/ncomms11005] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 02/10/2016] [Indexed: 01/09/2023] Open
Abstract
Numerical centrosome aberrations underlie certain developmental abnormalities and may promote cancer. A cell maintains normal centrosome numbers by coupling centrosome duplication with segregation, which is achieved through sustained association of each centrosome with a mitotic spindle pole. Although the microcephaly- and primordial dwarfism-linked centrosomal protein CEP215 has been implicated in this process, the molecular mechanism responsible remains unclear. Here, using proteomic profiling, we identify the minus end-directed microtubule motor protein HSET as a direct binding partner of CEP215. Targeted deletion of the HSET-binding domain of CEP215 in vertebrate cells causes centrosome detachment and results in HSET depletion at centrosomes, a phenotype also observed in CEP215-deficient patient-derived cells. Moreover, in cancer cells with centrosome amplification, the CEP215-HSET complex promotes the clustering of extra centrosomes into pseudo-bipolar spindles, thereby ensuring viable cell division. Therefore, stabilization of the centrosome-spindle pole interface by the CEP215-HSET complex could promote survival of cancer cells containing supernumerary centrosomes.
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Affiliation(s)
- Pavithra L. Chavali
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Robinson Way, Cambridge CB2 0RE, UK
| | - Gayathri Chandrasekaran
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Robinson Way, Cambridge CB2 0RE, UK
| | - Alexis R. Barr
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Robinson Way, Cambridge CB2 0RE, UK
| | - Péter Tátrai
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Robinson Way, Cambridge CB2 0RE, UK
| | - Chris Taylor
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Robinson Way, Cambridge CB2 0RE, UK
| | - Evaggelia K. Papachristou
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Robinson Way, Cambridge CB2 0RE, UK
| | - C. Geoffrey Woods
- Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
| | - Sreenivas Chavali
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Fanni Gergely
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Robinson Way, Cambridge CB2 0RE, UK
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42
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Chen JV, Kao LR, Jana SC, Sivan-Loukianova E, Mendonça S, Cabrera OA, Singh P, Cabernard C, Eberl DF, Bettencourt-Dias M, Megraw TL. Rootletin organizes the ciliary rootlet to achieve neuron sensory function in Drosophila. J Cell Biol 2015; 211:435-53. [PMID: 26483560 PMCID: PMC4621839 DOI: 10.1083/jcb.201502032] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 09/09/2015] [Indexed: 12/22/2022] Open
Abstract
Drosophila Rootletin organizes rootlets in sensory neurons, where it transmits multiple sensory inputs and maintains basal body cohesion, yet it is not required for cilium stability. Cilia are essential for cell signaling and sensory perception. In many cell types, a cytoskeletal structure called the ciliary rootlet links the cilium to the cell body. Previous studies indicated that rootlets support the long-term stability of some cilia. Here we report that Drosophila melanogaster Rootletin (Root), the sole orthologue of the mammalian paralogs Rootletin and C-Nap1, assembles into rootlets of diverse lengths among sensory neuron subtypes. Root mutant neurons lack rootlets and have dramatically impaired sensory function, resulting in behavior defects associated with mechanosensation and chemosensation. Root is required for cohesion of basal bodies, but the cilium structure appears normal in Root mutant neurons. We show, however, that normal rootlet assembly requires centrioles. The N terminus of Root contains a conserved domain and is essential for Root function in vivo. Ectopically expressed Root resides at the base of mother centrioles in spermatocytes and localizes asymmetrically to mother centrosomes in neuroblasts, both requiring Bld10, a basal body protein with varied functions.
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Affiliation(s)
- Jieyan V Chen
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL 32306
| | - Ling-Rong Kao
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL 32306
| | - Swadhin C Jana
- Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal
| | | | | | - Oscar A Cabrera
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL 32306
| | - Priyanka Singh
- Biozentrum, University of Basel, 4056 Basel, Switzerland
| | | | - Daniel F Eberl
- Biology Department, University of Iowa, Iowa City, IA 52242
| | | | - Timothy L Megraw
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL 32306
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43
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Lerit DA, Jordan HA, Poulton JS, Fagerstrom CJ, Galletta BJ, Peifer M, Rusan NM. Interphase centrosome organization by the PLP-Cnn scaffold is required for centrosome function. J Cell Biol 2015; 210:79-97. [PMID: 26150390 PMCID: PMC4494003 DOI: 10.1083/jcb.201503117] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Cnn and PLP directly interact at two defined sites to coordinate the cell cycle–dependent rearrangement and scaffolding activity of the centrosome to permit normal centrosome organization, cell division, and embryonic viability. Pericentriolar material (PCM) mediates the microtubule (MT) nucleation and anchoring activity of centrosomes. A scaffold organized by Centrosomin (Cnn) serves to ensure proper PCM architecture and functional changes in centrosome activity with each cell cycle. Here, we investigate the mechanisms that spatially restrict and temporally coordinate centrosome scaffold formation. Focusing on the mitotic-to-interphase transition in Drosophila melanogaster embryos, we show that the elaboration of the interphase Cnn scaffold defines a major structural rearrangement of the centrosome. We identify an unprecedented role for Pericentrin-like protein (PLP), which localizes to the tips of extended Cnn flares, to maintain robust interphase centrosome activity and promote the formation of interphase MT asters required for normal nuclear spacing, centrosome segregation, and compartmentalization of the syncytial embryo. Our data reveal that Cnn and PLP directly interact at two defined sites to coordinate the cell cycle–dependent rearrangement and scaffolding activity of the centrosome to permit normal centrosome organization, cell division, and embryonic viability.
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Affiliation(s)
- Dorothy A Lerit
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Holly A Jordan
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - John S Poulton
- Biology Department, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Carey J Fagerstrom
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Brian J Galletta
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Mark Peifer
- Biology Department, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Nasser M Rusan
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
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44
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Borek WE, Groocock LM, Samejima I, Zou J, de Lima Alves F, Rappsilber J, Sawin KE. Mto2 multisite phosphorylation inactivates non-spindle microtubule nucleation complexes during mitosis. Nat Commun 2015; 6:7929. [PMID: 26243668 PMCID: PMC4918325 DOI: 10.1038/ncomms8929] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 06/25/2015] [Indexed: 01/09/2023] Open
Abstract
Microtubule nucleation is highly regulated during the eukaryotic cell cycle, but the underlying molecular mechanisms are largely unknown. During mitosis in fission yeast Schizosaccharomyces pombe, cytoplasmic microtubule nucleation ceases simultaneously with intranuclear mitotic spindle assembly. Cytoplasmic nucleation depends on the Mto1/2 complex, which binds and activates the γ-tubulin complex and also recruits the γ-tubulin complex to both centrosomal (spindle pole body) and non-centrosomal sites. Here we show that the Mto1/2 complex disassembles during mitosis, coincident with hyperphosphorylation of Mto2 protein. By mapping and mutating multiple Mto2 phosphorylation sites, we generate mto2-phosphomutant strains with enhanced Mto1/2 complex stability, interaction with the γ-tubulin complex and microtubule nucleation activity. A mutant with 24 phosphorylation sites mutated to alanine, mto2[24A], retains interphase-like behaviour even in mitotic cells. This provides a molecular-level understanding of how phosphorylation ‘switches off' microtubule nucleation complexes during the cell cycle and, more broadly, illuminates mechanisms regulating non-centrosomal microtubule nucleation. In S. pombe, cytoplasmic microtubule nucleation, which depends on the Mto1/2 complex, ceases during mitosis. Here, Borek et al., show that multisite phosphorylation of Mto1/2 during mitosis disassembles the Mto1/2 complex and prevents microtubule nucleation activity.
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Affiliation(s)
- Weronika E Borek
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Lynda M Groocock
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Itaru Samejima
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Juan Zou
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Flavia de Lima Alves
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Juri Rappsilber
- 1] Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK [2] Department of Bioanalytics, Institute of Biotechnology, Technische Universität Berlin, Berlin 13355, Germany
| | - Kenneth E Sawin
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
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45
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Hanafusa H, Kedashiro S, Tezuka M, Funatsu M, Usami S, Toyoshima F, Matsumoto K. PLK1-dependent activation of LRRK1 regulates spindle orientation by phosphorylating CDK5RAP2. Nat Cell Biol 2015; 17:1024-35. [PMID: 26192437 DOI: 10.1038/ncb3204] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 06/12/2015] [Indexed: 12/14/2022]
Abstract
Correct formation of the cell division axis requires the initial precise orientation of the mitotic spindle. Proper spindle orientation depends on centrosome maturation, and Polo-like kinase 1 (PLK1) is known to play a crucial role in this process. However, the molecular mechanisms that function downstream of PLK1 are not well understood. Here we show that LRRK1 is a PLK1 substrate that is phosphorylated on Ser 1790. PLK1 phosphorylation is required for CDK1-mediated activation of LRRK1 at the centrosomes, and this in turn regulates mitotic spindle orientation by nucleating the growth of astral microtubules from the centrosomes. Interestingly, LRRK1 in turn phosphorylates CDK5RAP2(Cep215), a human homologue of Drosophila Centrosomin (Cnn), in its γ-tubulin-binding motif, thus promoting the interaction of CDK5RAP2 with γ-tubulin. LRRK1 phosphorylation of CDK5RAP2 Ser 140 is necessary for CDK5RAP2-dependent microtubule nucleation. Thus, our findings provide evidence that LRRK1 regulates mitotic spindle orientation downstream of PLK1 through CDK5RAP2-dependent centrosome maturation.
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Affiliation(s)
- Hiroshi Hanafusa
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Shin Kedashiro
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Motohiro Tezuka
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Motoki Funatsu
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Satoshi Usami
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Fumiko Toyoshima
- Department of Cell Biology, Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan
| | - Kunihiro Matsumoto
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
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46
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Abstract
Mutations in the pericentrin (PCNT) gene cause Majewski osteodysplastic primordial dwarfism type II (MOPDII). Recent work reveals that a discrete set of centrosome proteins require PCNT for their robust localization to mitotic spindle poles. Critically, this complex is crucial for mitotic spindle orientation and involved in the pathogenesis of MOPDII.
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Affiliation(s)
- Yi Luo
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario, M5G 1X5, Canada
| | - Laurence Pelletier
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario, M5G 1X5, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Ontario, M5S 1A8, Canada.
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47
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Abstract
The centrosome was discovered in the late 19th century when mitosis was first described. Long recognized as a key organelle of the spindle pole, its core component, the centriole, was realized more than 50 or so years later also to comprise the basal body of the cilium. Here, we chart the more recent acquisition of a molecular understanding of centrosome structure and function. The strategies for gaining such knowledge were quickly developed in the yeasts to decipher the structure and function of their distinctive spindle pole bodies. Only within the past decade have studies with model eukaryotes and cultured cells brought a similar degree of sophistication to our understanding of the centrosome duplication cycle and the multiple roles of this organelle and its component parts in cell division and signaling. Now as we begin to understand these functions in the context of development, the way is being opened up for studies of the roles of centrosomes in human disease.
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Affiliation(s)
- Jingyan Fu
- Cancer Research UK Cell Cycle Genetics Group, Department of Genetics, University of Cambridge, Cambridge CB2 3EH, United Kingdom
| | - Iain M Hagan
- Cancer Research UK Manchester Institute, University of Manchester, Withington, Manchester M20 4BX, United Kingdom
| | - David M Glover
- Cancer Research UK Cell Cycle Genetics Group, Department of Genetics, University of Cambridge, Cambridge CB2 3EH, United Kingdom
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48
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Tang NH, Okada N, Fong CS, Arai K, Sato M, Toda T. Targeting Alp7/TACC to the spindle pole body is essential for mitotic spindle assembly in fission yeast. FEBS Lett 2014; 588:2814-21. [PMID: 24937146 PMCID: PMC4158419 DOI: 10.1016/j.febslet.2014.06.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 05/12/2014] [Accepted: 06/03/2014] [Indexed: 01/09/2023]
Abstract
The conserved TACC protein family localises to the centrosome (the spindle pole body, SPB in fungi) and mitotic spindles, thereby playing a crucial role in bipolar spindle assembly. However, it remains elusive how TACC proteins are recruited to the centrosome/SPB. Here, using fission yeast Alp7/TACC, we have determined clustered five amino acid residues within the TACC domain required for SPB localisation. Critically, these sequences are essential for the functions of Alp7, including proper spindle formation and mitotic progression. Moreover, we have identified pericentrin-like Pcp1 as a loading factor to the mitotic SPB, although Pcp1 is not a sole platform.
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Affiliation(s)
- Ngang Heok Tang
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3LY, UK
| | - Naoyuki Okada
- Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan
| | - Chii Shyang Fong
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3LY, UK
| | - Kunio Arai
- Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan; Department of Life Science and Medical Bioscience, Graduate School of Advanced Science and Engineering, Waseda University, Center for Advanced Biomedical Sciences (TWIns), 2-2 Wakamatsucho, Shinjuku, Tokyo 162-8480, Japan
| | - Masamitsu Sato
- Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan; Department of Life Science and Medical Bioscience, Graduate School of Advanced Science and Engineering, Waseda University, Center for Advanced Biomedical Sciences (TWIns), 2-2 Wakamatsucho, Shinjuku, Tokyo 162-8480, Japan; PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Takashi Toda
- Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3LY, UK.
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49
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Zheng F, Li T, Jin DY, Syrovatkina V, Scheffler K, Tran PT, Fu C. Csi1p recruits alp7p/TACC to the spindle pole bodies for bipolar spindle formation. Mol Biol Cell 2014; 25:2750-60. [PMID: 25057016 PMCID: PMC4161510 DOI: 10.1091/mbc.e14-03-0786] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The spindle pole body (SPB) localization of the fission yeast Schizosaccharomyces pombe TACC orthologue alp7p depends on the SPB protein csi1p. Compromised interaction between csi1p and alp7p delays bipolar spindle formation and leads to abnormal chromosome segregation. Accurate chromosome segregation requires timely bipolar spindle formation during mitosis. The transforming acidic coiled-coil (TACC) family proteins and the ch-TOG family proteins are key players in bipolar spindle formation. They form a complex to stabilize spindle microtubules, mainly dependent on their localization to the centrosome (the spindle pole body [SPB] in yeast). The molecular mechanism underlying the targeting of the TACC–ch-TOG complex to the centrosome remains unclear. Here we show that the fission yeast Schizosaccharomyces pombe TACC orthologue alp7p is recruited to the SPB by csi1p. The csi1p-interacting region lies within the conserved TACC domain of alp7p, and the carboxyl-terminal domain of csi1p is responsible for interacting with alp7p. Compromised interaction between csi1p and alp7p impairs the localization of alp7p to the SPB during mitosis, thus delaying bipolar spindle formation and leading to anaphase B lagging chromosomes. Hence our study establishes that csi1p serves as a linking molecule tethering spindle-stabilizing factors to the SPB for promoting bipolar spindle assembly.
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Affiliation(s)
- Fan Zheng
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong, China HKU-Shenzhen Institute of Research and Innovation, University of Hong Kong, Shenzhen, China
| | - Tianpeng Li
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong, China HKU-Shenzhen Institute of Research and Innovation, University of Hong Kong, Shenzhen, China
| | - Dong-Yan Jin
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong, China
| | | | - Kathleen Scheffler
- Institut Curie, Centre National de la Recherche Scientifique, Paris 75005, France
| | - Phong T Tran
- Cell and Developmental Biology, University of Pennsylvania, Philadelphia, PA 10104 Institut Curie, Centre National de la Recherche Scientifique, Paris 75005, France
| | - Chuanhai Fu
- Department of Biochemistry, University of Hong Kong, Pokfulam, Hong Kong, China HKU-Shenzhen Institute of Research and Innovation, University of Hong Kong, Shenzhen, China
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50
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Galletta BJ, Guillen RX, Fagerstrom CJ, Brownlee CW, Lerit DA, Megraw TL, Rogers GC, Rusan NM. Drosophila pericentrin requires interaction with calmodulin for its function at centrosomes and neuronal basal bodies but not at sperm basal bodies. Mol Biol Cell 2014; 25:2682-94. [PMID: 25031429 PMCID: PMC4161505 DOI: 10.1091/mbc.e13-10-0617] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Pericentrin is a critical centrosomal protein required for organizing pericentriolar material (PCM) in mitosis. Mutations in pericentrin cause the human genetic disorder Majewski/microcephalic osteodysplastic primordial dwarfism type II, making a detailed understanding of its regulation extremely important. Germaine to pericentrin's function in organizing PCM is its ability to localize to the centrosome through the conserved C-terminal PACT domain. Here we use Drosophila pericentrin-like-protein (PLP) to understand how the PACT domain is regulated. We show that the interaction of PLP with calmodulin (CaM) at two highly conserved CaM-binding sites in the PACT domain controls the proper targeting of PLP to the centrosome. Disrupting the PLP-CaM interaction with single point mutations renders PLP inefficient in localizing to centrioles in cultured S2 cells and Drosophila neuroblasts. Although levels of PCM are unaffected, it is highly disorganized. We also demonstrate that basal body formation in the male testes and the production of functional sperm does not rely on the PLP-CaM interaction, whereas production of functional mechanosensory neurons does.
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Affiliation(s)
- Brian J Galletta
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Rodrigo X Guillen
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Carey J Fagerstrom
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Chris W Brownlee
- Department of Cellular and Molecular Medicine, University of Arizona Cancer Center, University of Arizona, Tucson, AZ 85724
| | - Dorothy A Lerit
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Timothy L Megraw
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL 32304
| | - Gregory C Rogers
- Department of Cellular and Molecular Medicine, University of Arizona Cancer Center, University of Arizona, Tucson, AZ 85724
| | - Nasser M Rusan
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
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