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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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2
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Haruta N, Sumiyoshi E, Honda Y, Terasawa M, Uchiyama C, Toya M, Kubota Y, Sugimoto A. A germline-specific role for unconventional components of the γ-tubulin complex in Caenorhabditis elegans. J Cell Sci 2023; 136:jcs260922. [PMID: 37313686 PMCID: PMC10657210 DOI: 10.1242/jcs.260922] [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: 12/29/2022] [Accepted: 06/07/2023] [Indexed: 06/15/2023] Open
Abstract
The γ-tubulin complex (γTuC) is a widely conserved microtubule nucleator, but some of its components, namely GCP4, GCP5 and GCP6 (also known as TUBGCP4, TUBGCP5 and TUBGCP6, respectively), have not been detected in Caenorhabditis elegans. Here, we identified two γTuC-associated proteins in C. elegans, GTAP-1 and GTAP-2, for which apparent orthologs were detected only in the genus Caenorhabditis. GTAP-1 and GTAP-2 were found to localize at centrosomes and the plasma membrane of the germline, and their centrosomal localization was interdependent. In early C. elegans embryos, whereas the conserved γTuC component MZT-1 (also known as MOZART1 and MZT1) was essential for the localization of centrosomal γ-tubulin, depletion of GTAP-1 and/or GTAP-2 caused up to 50% reduction of centrosomal γ-tubulin and precocious disassembly of spindle poles during mitotic telophase. In the adult germline, GTAP-1 and GTAP-2 contributed to efficient recruitment of the γTuC to the plasma membrane. Depletion of GTAP-1, but not of GTAP-2, severely disrupted both the microtubule array and the honeycomb-like structure of the adult germline. We propose that GTAP-1 and GTAP-2 are unconventional components of the γTuC that contribute to the organization of both centrosomal and non-centrosomal microtubules by targeting the γTuC to specific subcellular sites in a tissue-specific manner.
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Affiliation(s)
- Nami Haruta
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Eisuke Sumiyoshi
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Yu Honda
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Masahiro Terasawa
- Laboratory for Developmental Genomics, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan
| | - Chihiro Uchiyama
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Mika Toya
- Laboratory for Developmental Genomics, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan
| | - Yukihiko Kubota
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Asako Sugimoto
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
- Laboratory for Developmental Genomics, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan
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3
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Bartoszewski S, Dawidziuk M, Kasica N, Durak R, Jurek M, Podwysocka A, Guilbride DL, Podlasz P, Winata CL, Gawlinski P. A Zebrafish/Drosophila Dual System Model for Investigating Human Microcephaly. Cells 2022; 11:cells11172727. [PMID: 36078134 PMCID: PMC9455030 DOI: 10.3390/cells11172727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Revised: 08/27/2022] [Accepted: 08/28/2022] [Indexed: 12/02/2022] Open
Abstract
Microcephaly presents in neurodevelopmental disorders with multiple aetiologies, including bi-allelic mutation in TUBGCP2, a component of the biologically fundamental and conserved microtubule-nucleation complex, γ-TuRC. Elucidating underlying principles driving microcephaly requires clear phenotype recapitulation and assay reproducibility, areas where go-to experimental models fall short. We present an alternative simple vertebrate/invertebrate dual system to investigate fundamental TUBGCP2-related processes driving human microcephaly and associated developmental traits. We show that antisense morpholino knockdown (KD) of the Danio rerio homolog, tubgcp2, recapitulates human TUBGCP2-associated microcephaly. Co-injection of wild type mRNA pre-empts microcephaly in 55% of KD zebrafish larvae, confirming causality. Body shortening observed in morphants is also rescued. Mitotic marker (pH3) staining further reveals aberrantly accumulated dividing brain cells in microcephalic tubgcp2 KD morphants, indicating that tubgcp2 depletion disrupts normal mitosis and/or proliferation in zebrafish neural progenitor brain cells. Drosophila melanogaster double knockouts (KO) for TUBGCP2 homologs Grip84/cg7716 also develop microcephalic brains with general microsomia. Exacerbated Grip84/cg7716-linked developmental aberration versus single mutations strongly suggests interactive or coinciding gene functions. We infer that tubgcp2 and Grip84/cg7716 affect brain size similarly to TUBGCP2 and recapitulate both microcephaly and microcephaly-associated developmental impact, validating the zebrafish/fly research model for human microcephaly. Given the conserved cross-phyla homolog function, the data also strongly support mitotic and/or proliferative disruption linked to aberrant microtubule nucleation in progenitor brain cells as key mechanistic defects for human microcephaly.
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Affiliation(s)
- Slawomir Bartoszewski
- Department of Biology, Institute of Biology and Biotechnology, University of Rzeszów, 35-601 Rzeszów, Poland
| | - Mateusz Dawidziuk
- Department of Medical Genetics, Institute of Mother and Child, 01-211 Warsaw, Poland
| | - Natalia Kasica
- Department of Animal Anatomy, Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn, 10-719 Olsztyn, Poland
| | - Roma Durak
- Department of Biology, Institute of Biology and Biotechnology, University of Rzeszów, 35-601 Rzeszów, Poland
| | - Marta Jurek
- Department of Medical Genetics, Institute of Mother and Child, 01-211 Warsaw, Poland
| | - Aleksandra Podwysocka
- Department of Medical Genetics, Institute of Mother and Child, 01-211 Warsaw, Poland
| | | | - Piotr Podlasz
- Department of Pathophysiology, Forensic Veterinary Medicine and Administration, Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn, 10-719 Olsztyn, Poland
| | - Cecilia Lanny Winata
- Laboratory of Zebrafish Developmental Genomics, International Institute of Molecular and Cell Biology in Warsaw, 02-109 Warsaw, Poland
| | - Pawel Gawlinski
- Department of Medical Genetics, Institute of Mother and Child, 01-211 Warsaw, Poland
- Correspondence:
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4
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Gao X, Schmid M, Zhang Y, Fukuda S, Takeshita N, Fischer R. The spindle pole body of Aspergillus nidulans is asymmetrical and contains changing numbers of γ-tubulin complexes. J Cell Sci 2019; 132:jcs.234799. [PMID: 31740532 DOI: 10.1242/jcs.234799] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 10/28/2019] [Indexed: 12/14/2022] Open
Abstract
Centrosomes are important microtubule-organizing centers (MTOCs) in animal cells. In addition, non-centrosomal MTOCs (ncMTOCs) are found in many cell types. Their composition and structure are only poorly understood. Here, we analyzed nuclear MTOCs (spindle-pole bodies, SPBs) and septal MTOCs in Aspergillus nidulans They both contain γ-tubulin along with members of the family of γ-tubulin complex proteins (GCPs). Our data suggest that SPBs consist of γ-tubulin small complexes (γ-TuSCs) at the outer plaque, and larger γ-tubulin ring complexes (γ-TuRC) at the inner plaque. We show that the MztA protein, an ortholog of the human MOZART protein (also known as MZT1), interacted with the inner plaque receptor PcpA (the homolog of fission yeast Pcp1) at SPBs, while no interaction nor colocalization was detected between MztA and the outer plaque receptor ApsB (fission yeast Mto1). Septal MTOCs consist of γ-TuRCs including MztA but are anchored through AspB and Spa18 (fission yeast Mto2). MztA is not essential for viability, although abnormal spindles were observed frequently in cells lacking MztA. Quantitative PALM imaging revealed unexpected dynamics of the protein composition of SPBs, with changing numbers of γ-tubulin complexes over time during interphase and constant numbers during mitosis.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Xiaolei Gao
- Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Dept. of Microbiology, Fritz-Haber-Weg 4, D-76131 Karlsruhe, Germany
| | - Marjorie Schmid
- Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Dept. of Microbiology, Fritz-Haber-Weg 4, D-76131 Karlsruhe, Germany
| | - Ying Zhang
- Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Dept. of Microbiology, Fritz-Haber-Weg 4, D-76131 Karlsruhe, Germany
| | - Sayumi Fukuda
- Tsukuba University, Faculty of Life and Environmental Sciences, Tsukuba 305-8572, Japan
| | - Norio Takeshita
- Tsukuba University, Faculty of Life and Environmental Sciences, Tsukuba 305-8572, Japan
| | - Reinhard Fischer
- Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Dept. of Microbiology, Fritz-Haber-Weg 4, D-76131 Karlsruhe, Germany
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5
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Pavlova GA, Razuvaeva AV, Popova JV, Andreyeva EN, Yarinich LA, Lebedev MO, Pellacani C, Bonaccorsi S, Somma MP, Gatti M, Pindyurin AV. The role of Patronin in Drosophila mitosis. BMC Mol Cell Biol 2019; 20:7. [PMID: 31284878 PMCID: PMC6469034 DOI: 10.1186/s12860-019-0189-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Background The calmodulin-regulated spectrin-associated proteins (CAMSAPs) belong to a conserved protein family, which includes members that bind the polymerizing mcrotubule (MT) minus ends and remain associated with the MT lattice formed by minus end polymerization. Only one of the three mammalian CAMSAPs, CAMSAP1, localizes to the mitotic spindle but its function is unclear. In Drosophila, there is only one CAMSAP, named Patronin. Previous work has shown that Patronin stabilizes the minus ends of non-mitotic MTs and is required for proper spindle elongation. However, the precise role of Patronin in mitotic spindle assembly is poorly understood. Results Here we have explored the role of Patronin in Drosophila mitosis using S2 tissue culture cells as a model system. We show that Patronin associates with different types of MT bundles within the Drosophila mitotic spindle, and that it is required for their stability. Imaging of living cells expressing Patronin-GFP showed that Patronin displays a dynamic behavior. In prometaphase cells, Patronin accumulates on short segments of MT bundles located near the chromosomes. These Patronin “seeds” extend towards the cell poles and stop growing just before reaching the poles. Our data also suggest that Patronin localization is largely independent of proteins acting at the MT minus ends such as Asp and Klp10A. Conclusion Our results suggest a working hypothesis about the mitotic role of Patronin. We propose that Patronin binds the minus ends within MT bundles, including those generated from the walls of preexisting MTs via the augmin-mediated pathway. This would help maintaining MT association within the mitotic bundles, thereby stabilizing the spindle structure. Our data also raise the intriguing possibility that the minus ends of bundled MTs can undergo a limited polymerization. Electronic supplementary material The online version of this article (10.1186/s12860-019-0189-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Gera A Pavlova
- Institute of Molecular and Cellular Biology, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia
| | - Alyona V Razuvaeva
- Institute of Molecular and Cellular Biology, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Julia V Popova
- Institute of Molecular and Cellular Biology, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia
| | - Evgeniya N Andreyeva
- Institute of Molecular and Cellular Biology, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia
| | - Lyubov A Yarinich
- Institute of Molecular and Cellular Biology, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Mikhail O Lebedev
- Institute of Molecular and Cellular Biology, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia.,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - Claudia Pellacani
- IBPM CNR and Department of Biology and Biotechnology, Sapienza University of Rome, 00185, Rome, Italy
| | - Silvia Bonaccorsi
- IBPM CNR and Department of Biology and Biotechnology, Sapienza University of Rome, 00185, Rome, Italy
| | - Maria Patrizia Somma
- IBPM CNR and Department of Biology and Biotechnology, Sapienza University of Rome, 00185, Rome, Italy
| | - Maurizio Gatti
- Institute of Molecular and Cellular Biology, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia. .,IBPM CNR and Department of Biology and Biotechnology, Sapienza University of Rome, 00185, Rome, Italy.
| | - Alexey V Pindyurin
- Institute of Molecular and Cellular Biology, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia. .,Novosibirsk State University, Novosibirsk, 630090, Russia.
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6
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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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7
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γ-Tubulin small complex formation is essential for early zebrafish embryogenesis. Mech Dev 2018; 154:145-152. [DOI: 10.1016/j.mod.2018.06.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 06/28/2018] [Accepted: 06/28/2018] [Indexed: 01/01/2023]
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8
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Romé P, Ohkura H. A novel microtubule nucleation pathway for meiotic spindle assembly in oocytes. J Cell Biol 2018; 217:3431-3445. [PMID: 30087124 PMCID: PMC6168254 DOI: 10.1083/jcb.201803172] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 04/10/2018] [Accepted: 07/18/2018] [Indexed: 12/25/2022] Open
Abstract
The meiotic spindle in oocytes is assembled in the absence of centrosomes, the major microtubule nucleation sites in mitotic and male meiotic cells. A crucial, yet unresolved question in meiosis is how spindle microtubules are generated without centrosomes and only around chromosomes in the exceptionally large volume of oocytes. Here we report a novel oocyte-specific microtubule nucleation pathway that is essential for assembling most spindle microtubules complementarily with the Augmin pathway. This pathway is mediated by the kinesin-6 Subito/MKlp2, which recruits the γ-tubulin complex to the spindle equator to nucleate microtubules in Drosophila oocytes. Away from chromosomes, Subito interaction with the γ-tubulin complex is suppressed by its N-terminal region to prevent ectopic microtubule assembly in oocytes. We further demonstrate in vitro that the Subito complex from ovaries can nucleate microtubules from pure tubulin dimers. Collectively, microtubule nucleation regulated by Subito drives spatially restricted spindle assembly in oocytes.
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Affiliation(s)
- Pierre Romé
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Scotland, UK
| | - Hiroyuki Ohkura
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Scotland, UK
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9
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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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10
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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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11
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Lin TC, Neuner A, Flemming D, Liu P, Chinen T, Jäkle U, Arkowitz R, Schiebel E. MOZART1 and γ-tubulin complex receptors are both required to turn γ-TuSC into an active microtubule nucleation template. J Cell Biol 2016; 215:823-840. [PMID: 27920216 PMCID: PMC5166503 DOI: 10.1083/jcb.201606092] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 10/03/2016] [Accepted: 11/04/2016] [Indexed: 01/14/2023] Open
Abstract
Cells use γ-tubulin complex to nucleate microtubules. The assembly of active microtubule nucleator is spatially and temporally regulated through the cell cycle. Lin et al. show that the protein Mzt1/MOZART1 and γ-tubulin complex receptors directly interact and act together to assemble the γ-tubulin small complex into an active microtubule nucleation template and that such interaction is conserved between Candida albicans and human cells. MOZART1/Mzt1 is required for the localization of γ-tubulin complexes to microtubule (MT)–organizing centers from yeast to human cells. Nevertheless, the molecular function of MOZART1/Mzt1 is largely unknown. Taking advantage of the minimal MT nucleation system of Candida albicans, we reconstituted the interactions of Mzt1, γ-tubulin small complex (γ-TuSC), and γ-tubulin complex receptors (γ-TuCRs) Spc72 and Spc110 in vitro. With affinity measurements, domain deletion, and swapping, we show that Spc110 and Mzt1 bind to distinct regions of the γ-TuSC. In contrast, both Mzt1 and γ-TuSC interact with the conserved CM1 motif of Spc110/Spc72. Spc110/Spc72 and Mzt1 constitute “oligomerization chaperones,” cooperatively promoting and directing γ-TuSC oligomerization into MT nucleation-competent rings. Consistent with the functions of Mzt1, human MOZART1 directly interacts with the CM1-containing region of the γ-TuCR CEP215. MOZART1 depletion in human cells destabilizes the large γ-tubulin ring complex and abolishes CEP215CM1-induced ectopic MT nucleation. Together, we reveal conserved functions of MOZART1/Mzt1 through interactions with γ-tubulin complex subunits and γ-TuCRs.
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Affiliation(s)
- Tien-Chen Lin
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH-Allianz, 69120 Heidelberg, Germany
| | - Annett Neuner
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH-Allianz, 69120 Heidelberg, Germany
| | | | - Peng Liu
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH-Allianz, 69120 Heidelberg, Germany
| | - Takumi Chinen
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH-Allianz, 69120 Heidelberg, Germany
| | - Ursula Jäkle
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH-Allianz, 69120 Heidelberg, Germany
| | - Robert Arkowitz
- Université Côte d'Azur, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut de Biologie Valrose, 06108 Nice, France
| | - Elmar Schiebel
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH-Allianz, 69120 Heidelberg, Germany
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12
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Oakley BR, Paolillo V, Zheng Y. γ-Tubulin complexes in microtubule nucleation and beyond. Mol Biol Cell 2015; 26:2957-62. [PMID: 26316498 PMCID: PMC4551311 DOI: 10.1091/mbc.e14-11-1514] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 07/02/2015] [Accepted: 07/02/2015] [Indexed: 01/07/2023] Open
Abstract
Tremendous progress has been made in understanding the functions of γ-tubulin and, in particular, its role in microtubule nucleation since the publication of its discovery in 1989. The structure of γ-tubulin has been determined, and the components of γ-tubulin complexes have been identified. Significant progress in understanding the structure of the γ-tubulin ring complex and its components has led to a persuasive model for how these complexes nucleate microtubule assembly. At the same time, data have accumulated that γ-tubulin has important but less well understood functions that are not simply a consequence of its function in microtubule nucleation. These include roles in the regulation of plus-end microtubule dynamics, gene regulation, and mitotic and cell cycle regulation. Finally, evidence is emerging that γ-tubulin mutations or alterations of γ-tubulin expression play an important role in certain types of cancer and in other diseases.
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Affiliation(s)
- Berl R Oakley
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045
| | - Vitoria Paolillo
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045
| | - Yixian Zheng
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218
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13
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Bouissou A, Vérollet C, de Forges H, Haren L, Bellaïche Y, Perez F, Merdes A, Raynaud-Messina B. γ-Tubulin Ring Complexes and EB1 play antagonistic roles in microtubule dynamics and spindle positioning. EMBO J 2014; 33:114-28. [PMID: 24421324 DOI: 10.1002/embj.201385967] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
γ-Tubulin is critical for microtubule (MT) assembly and organization. In metazoa, this protein acts in multiprotein complexes called γ-Tubulin Ring Complexes (γ-TuRCs). While the subunits that constitute γ-Tubulin Small Complexes (γ-TuSCs), the core of the MT nucleation machinery, are essential, mutation of γ-TuRC-specific proteins in Drosophila causes sterility and morphological abnormalities via hitherto unidentified mechanisms. Here, we demonstrate a role of γ-TuRCs in controlling spindle orientation independent of MT nucleation activity, both in cultured cells and in vivo, and examine a potential function for γ-TuRCs on astral MTs. γ-TuRCs locate along the length of astral MTs, and depletion of γ-TuRC-specific proteins increases MT dynamics and causes the plus-end tracking protein EB1 to redistribute along MTs. Moreover, suppression of MT dynamics through drug treatment or EB1 down-regulation rescues spindle orientation defects induced by γ-TuRC depletion. Therefore, we propose a role for γ-TuRCs in regulating spindle positioning by controlling the stability of astral MTs.
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Affiliation(s)
- Anaïs Bouissou
- Centre Biologie du Développement, UMR 5547 CNRS-UPS Toulouse 3, Toulouse Cedex 04, France
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14
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LGALS3BP regulates centriole biogenesis and centrosome hypertrophy in cancer cells. Nat Commun 2013; 4:1531. [PMID: 23443559 DOI: 10.1038/ncomms2517] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 01/17/2013] [Indexed: 12/18/2022] Open
Abstract
Centrosome morphology and number are frequently deregulated in cancer cells. Here, to identify factors that are functionally relevant for centrosome abnormalities in cancer cells, we established a protein-interaction network around 23 centrosomal and cell-cycle regulatory proteins, selecting the interacting proteins that are deregulated in cancer for further studies. One of these components, LGALS3BP, is a centriole- and basal body-associated protein with a dual role, triggering centrosome hypertrophy when overexpressed and causing accumulation of centriolar substructures when downregulated. The cancer cell line SK-BR-3 that overexpresses LGALS3BP exhibits hypertrophic centrosomes, whereas in seminoma tissues with low expression of LGALS3BP, supernumerary centriole-like structures are present. Centrosome hypertrophy is reversed by depleting LGALS3BP in cells endogenously overexpressing this protein, supporting a direct role in centrosome aberration. We propose that LGALS3BP suppresses assembly of centriolar substructures, and when depleted, causes accumulation of centriolar complexes comprising CPAP, acetylated tubulin and centrin.
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15
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Virtual and biophysical screening targeting the γ-tubulin complex--a new target for the inhibition of microtubule nucleation. PLoS One 2013; 8:e63908. [PMID: 23691113 PMCID: PMC3655011 DOI: 10.1371/journal.pone.0063908] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 04/08/2013] [Indexed: 01/11/2023] Open
Abstract
Microtubules are the main constituents of mitotic spindles. They are nucleated in large amounts during spindle assembly, from multiprotein complexes containing γ-tubulin and associated γ-tubulin complex proteins (GCPs). With the aim of developing anti-cancer drugs targeting these nucleating complexes, we analyzed the interface between GCP4 and γ-tubulin proteins usually located in a multiprotein complex named γ-TuRC (γ-Tubulin Ring Complex). 10 ns molecular dynamics simulations were performed on the heterodimers to obtain a stable complex in silico and to analyze the residues involved in persistent protein-protein contacts, responsible for the stability of the complex. We demonstrated in silico the existence of a binding pocket at the interface between the two proteins upon complex formation. By combining virtual screening using a fragment-based approach and biophysical screening, we found several small molecules that bind specifically to this pocket. Sub-millimolar fragments have been experimentally characterized on recombinant proteins using differential scanning fluorimetry (DSF) for validation of these compounds as inhibitors. These results open a new avenue for drug development against microtubule-nucleating γ-tubulin complexes.
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16
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Remy MH, Merdes A, Gregory-Pauron L. Assembly of Gamma-Tubulin Ring Complexes. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 117:511-30. [DOI: 10.1016/b978-0-12-386931-9.00019-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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17
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Reschen RF, Colombie N, Wheatley L, Dobbelaere J, St Johnston D, Ohkura H, Raff JW. Dgp71WD is required for the assembly of the acentrosomal Meiosis I spindle, and is not a general targeting factor for the γ-TuRC. Biol Open 2012; 1:422-9. [PMID: 23213433 PMCID: PMC3507215 DOI: 10.1242/bio.2012596] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Dgp71WD/Nedd1 proteins are essential for mitotic spindle formation. In human cells, Nedd1 targets γ-tubulin to both centrosomes and spindles, but in other organisms the function of Dgp71WD/Nedd1 is less clear. In Drosophila cells, Dgp71WD plays a major part in targeting γ-tubulin to spindles, but not centrosomes, while in Xenopus egg extracts, Nedd1 acts as a more general microtubule (MT) organiser that can function independently of γ-tubulin. The interpretation of these studies, however, is complicated by the fact that some residual Dgp71WD/Nedd1 is likely present in the cells/extracts analysed. Here we generate a Dgp71WD null mutant lacking all but the last 12 nucleotides of coding sequence. The complete loss of Dgp71WD has no quantifiable effect on γ-tubulin or Centrosomin recruitment to the centrosome in larval brain cells. The recruitment of γ-tubulin to spindle MTs, however, is severely impaired, and spindle MT density is reduced in a manner that is indistinguishable from cells lacking Augmin or γ-TuRC function. In contrast, the absence of Dgp71WD leads to defects in the assembly of the acentrosomal female Meiosis I spindle that are more severe than those seen in Augmin or γ-TuRC mutants, indicating that Dgp71WD has additional functions that are independent of these complexes in oocytes. Moreover, the localisation of bicoid RNA during oogenesis, which requires γ-TuRC function, is unperturbed in Dgp71WD(120) mutants. Thus, Dgp71WD is not simply a general cofactor required for γ-TuRC and/or Augmin targeting, and it appears to have a crucial role independent of these complexes in the acentrosomal Meiosis I spindle.
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Affiliation(s)
- Richard F. Reschen
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Nathalie Colombie
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh, EH9 3JR, UK
| | - Lucy Wheatley
- Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
| | - Jeroen Dobbelaere
- Research Institute of Molecular Pathology (IMP), Dr. Bohr-Gasse 7, 1030 Vienna, Austria
| | - Daniel St Johnston
- Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
| | - Hiro Ohkura
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Michael Swann Building, Kings Buildings, Mayfield Road, Edinburgh, EH9 3JR, UK
| | - Jordan W. Raff
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
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18
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Janski N, Masoud K, Batzenschlager M, Herzog E, Evrard JL, Houlné G, Bourge M, Chabouté ME, Schmit AC. The GCP3-interacting proteins GIP1 and GIP2 are required for γ-tubulin complex protein localization, spindle integrity, and chromosomal stability. THE PLANT CELL 2012; 24:1171-87. [PMID: 22427335 PMCID: PMC3336128 DOI: 10.1105/tpc.111.094904] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Revised: 02/03/2012] [Accepted: 02/27/2012] [Indexed: 05/18/2023]
Abstract
Microtubules (MTs) are crucial for both the establishment of cellular polarity and the progression of all mitotic phases leading to karyokinesis and cytokinesis. MT organization and spindle formation rely on the activity of γ-tubulin and associated proteins throughout the cell cycle. To date, the molecular mechanisms modulating γ-tubulin complex location remain largely unknown. In this work, two Arabidopsis thaliana proteins interacting with gamma-tubulin complex protein3 (GCP3), GCP3-interacting protein1 (GIP1) and GIP2, have been characterized. Both GIP genes are ubiquitously expressed in all tissues analyzed. Immunolocalization studies combined with the expression of GIP-green fluorescent protein fusions have shown that GIPs colocalize with γ-tubulin, GCP3, and/or GCP4 and reorganize from the nucleus to the prospindle and the preprophase band in late G2. After nuclear envelope breakdown, they localize on spindle and phragmoplast MTs and on the reforming nuclear envelope of daughter cells. The gip1 gip2 double mutants exhibit severe growth defects and sterility. At the cellular level, they are characterized by MT misorganization and abnormal spindle polarity, resulting in ploidy defects. Altogether, our data show that during mitosis GIPs play a role in γ-tubulin complex localization, spindle stability and chromosomal segregation.
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Affiliation(s)
- Natacha Janski
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, Unité Propre de Recherche 2357, Conventionné avec l’Université de Strasbourg, 67084 Strasbourg, France
| | - Kinda Masoud
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, Unité Propre de Recherche 2357, Conventionné avec l’Université de Strasbourg, 67084 Strasbourg, France
| | - Morgane Batzenschlager
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, Unité Propre de Recherche 2357, Conventionné avec l’Université de Strasbourg, 67084 Strasbourg, France
| | - Etienne Herzog
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, Unité Propre de Recherche 2357, Conventionné avec l’Université de Strasbourg, 67084 Strasbourg, France
| | - Jean-Luc Evrard
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, Unité Propre de Recherche 2357, Conventionné avec l’Université de Strasbourg, 67084 Strasbourg, France
| | - Guy Houlné
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, Unité Propre de Recherche 2357, Conventionné avec l’Université de Strasbourg, 67084 Strasbourg, France
| | - Mickael Bourge
- Laboratoire Dynamique de la Compartimentation Cellulaire, Institut des Sciences du Végétal, Centre National de la Recherche Scientifique, Unité Propre de Recherche 2355/Institut Fédératif de Recherche 87, Centre de Recherche de Gif (Fédération de Recherche du Centre National de la Recherche Scientifique 115), 91198 Gif-sur-Yvette cedex, France
| | - Marie-Edith Chabouté
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, Unité Propre de Recherche 2357, Conventionné avec l’Université de Strasbourg, 67084 Strasbourg, France
| | - Anne-Catherine Schmit
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, Unité Propre de Recherche 2357, Conventionné avec l’Université de Strasbourg, 67084 Strasbourg, France
- Address correspondence to
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19
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Spindle assembly defects leading to the formation of a monopolar mitotic apparatus. Biol Cell 2012; 101:1-11. [DOI: 10.1042/bc20070162] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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20
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Sun SC, Kim NH. Spindle assembly checkpoint and its regulators in meiosis. Hum Reprod Update 2011; 18:60-72. [DOI: 10.1093/humupd/dmr044] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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21
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Lin TC, Gombos L, Neuner A, Sebastian D, Olsen JV, Hrle A, Benda C, Schiebel E. Phosphorylation of the yeast γ-tubulin Tub4 regulates microtubule function. PLoS One 2011; 6:e19700. [PMID: 21573187 PMCID: PMC3088709 DOI: 10.1371/journal.pone.0019700] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Accepted: 04/11/2011] [Indexed: 01/10/2023] Open
Abstract
The yeast γ-tubulin Tub4 is assembled with Spc97 and Spc98 into the small Tub4 complex. The Tub4 complex binds via the receptor proteins Spc72 and Spc110 to the spindle pole body (SPB), the functional equivalent of the mammalian centrosome, where the Tub4 complex organizes cytoplasmic and nuclear microtubules. Little is known about the regulation of the Tub4 complex. Here, we isolated the Tub4 complex with the bound receptors from yeast cells. Analysis of the purified Tub4 complex by mass spectrometry identified more than 50 phosphorylation sites in Spc72, Spc97, Spc98, Spc110 and Tub4. To examine the functional relevance of the phosphorylation sites, phospho-mimicking and non-phosphorylatable mutations in Tub4, Spc97 and Spc98 were analyzed. Three phosphorylation sites in Tub4 were found to be critical for Tub4 stability and microtubule organization. One of the sites is highly conserved in γ-tubulins from yeast to human.
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Affiliation(s)
- Tien-chen Lin
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Linda Gombos
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Annett Neuner
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Dominik Sebastian
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | | | - Ajla Hrle
- MPI Biochemistry, Martinsried, Germany
| | | | - Elmar Schiebel
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
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22
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Müller H, Schmidt D, Steinbrink S, Mirgorodskaya E, Lehmann V, Habermann K, Dreher F, Gustavsson N, Kessler T, Lehrach H, Herwig R, Gobom J, Ploubidou A, Boutros M, Lange BMH. Proteomic and functional analysis of the mitotic Drosophila centrosome. EMBO J 2010; 29:3344-57. [PMID: 20818332 PMCID: PMC2957212 DOI: 10.1038/emboj.2010.210] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Accepted: 08/04/2010] [Indexed: 11/09/2022] Open
Abstract
Regulation of centrosome structure, duplication and segregation is integrated into cellular pathways that control cell cycle progression and growth. As part of these pathways, numerous proteins with well-established non-centrosomal localization and function associate with the centrosome to fulfill regulatory functions. In turn, classical centrosomal components take up functional and structural roles as part of other cellular organelles and compartments. Thus, although a comprehensive inventory of centrosome components is missing, emerging evidence indicates that its molecular composition reflects the complexity of its functions. We analysed the Drosophila embryonic centrosomal proteome using immunoisolation in combination with mass spectrometry. The 251 identified components were functionally characterized by RNA interference. Among those, a core group of 11 proteins was critical for centrosome structure maintenance. Depletion of any of these proteins in Drosophila SL2 cells resulted in centrosome disintegration, revealing a molecular dependency of centrosome structure on components of the protein translation machinery, actin- and RNA-binding proteins. In total, we assigned novel centrosome-related functions to 24 proteins and confirmed 13 of these in human cells.
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Affiliation(s)
- Hannah Müller
- Department of Vertebrate Genomics, Max-Planck Institute for Molecular Genetics, Berlin, Germany
| | - David Schmidt
- Leibniz Institute for Age Research—Fritz Lipmann Institute, Jena, Germany
| | - Sandra Steinbrink
- German Cancer Research Center (DKFZ), Division of Signaling and Functional Genomics and University of Heidelberg, Faculty of Medicine Mannheim, Department of Cell and Molecular Biology, Heidelberg, Germany
| | - Ekaterina Mirgorodskaya
- Department of Vertebrate Genomics, Max-Planck Institute for Molecular Genetics, Berlin, Germany
| | - Verena Lehmann
- Department of Vertebrate Genomics, Max-Planck Institute for Molecular Genetics, Berlin, Germany
| | - Karin Habermann
- Department of Vertebrate Genomics, Max-Planck Institute for Molecular Genetics, Berlin, Germany
| | - Felix Dreher
- Department of Vertebrate Genomics, Max-Planck Institute for Molecular Genetics, Berlin, Germany
| | - Niklas Gustavsson
- Department of Vertebrate Genomics, Max-Planck Institute for Molecular Genetics, Berlin, Germany
| | - Thomas Kessler
- Department of Vertebrate Genomics, Max-Planck Institute for Molecular Genetics, Berlin, Germany
| | - Hans Lehrach
- Department of Vertebrate Genomics, Max-Planck Institute for Molecular Genetics, Berlin, Germany
| | - Ralf Herwig
- Department of Vertebrate Genomics, Max-Planck Institute for Molecular Genetics, Berlin, Germany
| | - Johan Gobom
- Department of Vertebrate Genomics, Max-Planck Institute for Molecular Genetics, Berlin, Germany
| | - Aspasia Ploubidou
- Leibniz Institute for Age Research—Fritz Lipmann Institute, Jena, Germany
| | - Michael Boutros
- German Cancer Research Center (DKFZ), Division of Signaling and Functional Genomics and University of Heidelberg, Faculty of Medicine Mannheim, Department of Cell and Molecular Biology, Heidelberg, Germany
| | - Bodo M H Lange
- Department of Vertebrate Genomics, Max-Planck Institute for Molecular Genetics, Berlin, Germany
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23
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A developmentally regulated two-step process generates a noncentrosomal microtubule network in Drosophila tracheal cells. Dev Cell 2010; 18:790-801. [PMID: 20493812 DOI: 10.1016/j.devcel.2010.03.015] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2009] [Revised: 01/22/2010] [Accepted: 03/12/2010] [Indexed: 02/01/2023]
Abstract
Microtubules (MTs) are essential for many cell features, such as polarity, motility, shape, and vesicle trafficking. Therefore, in a multicellular organism, their organization differs between cell types and during development; however, the control of this process remains elusive. Here, we show that during Drosophila tracheal morphogenesis, MT reorganization is coupled to relocalization of the microtubule organizing centers (MTOC) components from the centrosome to the apical cell domain from where MTs then grow. We reveal that this process is controlled by the trachealess patterning gene in a two-step mechanism. MTOC components are first released from the centrosome by the activity of the MT-severing protein Spastin, and then anchored apically through the transmembrane protein Piopio. We further show that these changes are essential for tracheal development, thus stressing the functional relevance of MT reorganization for morphogenesis.
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24
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Xiong Y, Oakley BR. In vivo analysis of the functions of gamma-tubulin-complex proteins. J Cell Sci 2009; 122:4218-27. [PMID: 19861490 DOI: 10.1242/jcs.059196] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To enhance our understanding of the function(s) of gamma-tubulin-complex proteins (GCPs), we identified and analyzed the functions of the Aspergillus nidulans homologs of GCP2-GCP6 (here designated GCPB-GCBF). The gamma-tubulin small complex (gamma-TuSC) components, gamma-tubulin, GCPB and GCPC, are essential for viability and mitotic spindle formation, whereas GCPD-GCPF are not essential for viability, spindle formation or sexual reproduction. GCPD-GCPF function in reducing the frequency of chromosome mis-segregation and in the assembly of large gamma-tubulin complexes. Deletion of any of the gamma-TuSC components eliminates the localization of all GCPs to the spindle pole body (SPB), whereas deletion of GCPD-GCPF does not affect localization of gamma-TuSC components. Thus, GCPD-GCPF do not tether the gamma-TuSC to the SPB, but, rather, the gamma-TuSC tethers them to the SPB. GCPD-GCPF exhibit a hierarchy of localization to the SPB. Deletion of GCPF eliminates GCPD-GCPE localization to the SPB, and deletion of GCPD eliminates GCPE (but not GCPF) localization. All GCPs localize normally in a GCPE deletion. We propose a model for the structure of the gamma-tubulin complex and its attachment to polar microtubule organizing centers.
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Affiliation(s)
- Yi Xiong
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
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25
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Bouissou A, Vérollet C, Sousa A, Sampaio P, Wright M, Sunkel CE, Merdes A, Raynaud-Messina B. {gamma}-Tubulin ring complexes regulate microtubule plus end dynamics. ACTA ACUST UNITED AC 2009; 187:327-34. [PMID: 19948476 PMCID: PMC2779254 DOI: 10.1083/jcb.200905060] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Independently of their nucleation activity, γ-tubulin ring complex proteins localize along microtubules, limiting catastrophe events during interphase. γ-Tubulin is critical for the initiation and regulation of microtubule (MT) assembly. In Drosophila melanogaster, it acts within two main complexes: the γ-tubulin small complex (γ-TuSC) and the γ-tubulin ring complex (γ-TuRC). Proteins specific of the γ-TuRC, although nonessential for viability, are required for efficient mitotic progression. Until now, their role during interphase remained poorly understood. Using RNA interference in Drosophila S2 cells, we show that the γ-TuRC is not critical for overall MT organization. However, depletion of any component of this complex results in an increase of MT dynamics. Combined immunofluorescence and live imaging analysis allows us to reveal that the γ-TuRC localizes along interphase MTs and that distal γ-tubulin spots match with sites of pause or rescue events. We propose that, in addition to its role in nucleation, the γ-TuRC associated to MTs may regulate their dynamics by limiting catastrophes.
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Affiliation(s)
- Anaïs Bouissou
- Centre de Recherche en Pharmacologie-Santé, Unité Mixte de Recherche 2587 Centre National de la Recherche Scientifique-Pierre Fabre, 31400 Toulouse, France
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26
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Nakamura M, Hashimoto T. A mutation in the Arabidopsis γ-tubulin-containing complex causes helical growth and abnormal microtubule branching. J Cell Sci 2009; 122:2208-17. [DOI: 10.1242/jcs.044131] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plant cortical microtubules are mainly nucleated on previously established microtubules, grow at a narrow range of angles to the wall of mother microtubules, and eventually are released from the nucleation sites. These nucleation events are thought to be regulated by γ-tubulin-containing complexes. We here show that a null mutation of Arabidopsis GCP2, a core subunit of the γ-tubulin-containing complex, severely impaired the development of male and female gametophytes. However, a missense mutation in the conserved grip1 motif, called spiral3, caused a left-handed helical organization of cortical microtubule arrays, and severe right-handed helical growth. The spiral3 mutation compromises interaction between GCP2 and GCP3, another subunit of the complex, in yeast. In the spiral3 mutant, microtubule dynamics and nucleation efficiency were not markedly affected, but nucleating angles were wider and more divergently distributed. A spiral3 katanin double mutant had swollen and twisted epidermal cells, and showed that the microtubule minus ends were not released from the nucleation sites, although the nucleating angles distributed in a similar manner to those in spiral3. These results show that Arabidopsis GCP2 has an important role in precisely positioning the γ-tubulin-containing complex on pre-existing microtubules and in the proper organization of cortical arrays.
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Affiliation(s)
- Masayoshi Nakamura
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Takashi Hashimoto
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
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27
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Fant X, Gnadt N, Haren L, Merdes A. Stability of the small gamma-tubulin complex requires HCA66, a protein of the centrosome and the nucleolus. J Cell Sci 2009; 122:1134-44. [PMID: 19299467 DOI: 10.1242/jcs.035238] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
To investigate changes at the centrosome during the cell cycle, we analyzed the composition of the pericentriolar material from unsynchronized and S-phase-arrested cells by gel electrophoresis and mass spectrometry. We identified HCA66, a protein that localizes to the centrosome from S-phase to mitosis and to the nucleolus throughout interphase. Silencing of HCA66 expression resulted in failure of centrosome duplication and in the formation of monopolar spindles, reminiscent of the phenotype observed after gamma-tubulin silencing. Immunofluorescence microscopy showed that proteins of the gamma-tubulin ring complex were absent from the centrosome in these monopolar spindles. Immunoblotting revealed reduced protein levels of all components of the gamma-tubulin small complex (gamma-tubulin, GCP2, and GCP3) in HCA66-depleted cells. By contrast, the levels of gamma-tubulin ring complex proteins such as GCP4 and GCP-WD/NEDD1 were unaffected. We propose that HCA66 is a novel regulator of gamma-tubulin function that plays a role in stabilizing components of the gamma-tubulin small complex, which is in turn essential for assembling the larger gamma-tubulin ring complex.
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Affiliation(s)
- Xavier Fant
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JR, UK
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28
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Abstract
Tight regulation of centrosome duplication is critical to ensure that centrosome number doubles once and only once per cell cycle. Superimposed onto this centrosome duplication cycle is a functional centrosome cycle in which they alternate between phases of quiescence and robust microtubule (MT) nucleation and MT-anchoring activities. In vertebrate cycling cells, interphase centrioles accumulate less pericentriolar material (PCM), reducing their MT nucleation capacity. In mitosis, centrosomes mature, accumulating more PCM to increase their nucleation and anchoring capacities to form robust MT asters. Interestingly, functional cycles of centrosomes can be altered to suit the cell's needs. Some interphase centrosomes function as a microtubule-organizing center by increasing their ability to anchor MTs to form centrosomal radial arrays. Other interphase centrosomes maintain their MT nucleation capacity but reduce/eliminate their MT-anchoring capacity. Recent work demonstrates that Drosophila cells take this to the extreme, whereby centrioles lose all detectable PCM during interphase, offering an explanation as to how centrosome-deficient flies develop to adulthood. Drosophila stem cells further modify the functional cycle by differentially regulating their two centrioles - a situation that seems important for stem cell asymmetric divisions, as misregulation of centrosome duplication in stem/progenitor cells can promote tumor formation. Here, we review recent findings that describe variations in the functional cycle of centrosomes.
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Affiliation(s)
- Nasser M Rusan
- Department of Biology, University of North Carolina at Chapel Hill, CB#3280, Coker Hall, Chapel Hill, NC 27599, USA.
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29
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Liu T, Niu Y, Yu Y, Liu Y, Zhang F. Increased gamma-tubulin expression and P16INK4A promoter methylation occur together in preinvasive lesions and carcinomas of the breast. Ann Oncol 2009; 20:441-8. [PMID: 19131428 DOI: 10.1093/annonc/mdn651] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Loss of p16(INK4A) due to promoter hypermethylation is correlated with the ability to acquire centrosomal abnormalities in variant human mammary epithelial cells. gamma-Tubulin is a highly conserved component of centrosome in most animal cells and gamma-tubulin protein overexpression could lead to centrosome aberration. MATERIALS AND METHODS A large series of breast premalignant lesions and carcinoma was analyzed. Real-time quantitative PCR and immunohistochemistry were carried out to measure gamma-tubulin copy numbers and protein expression. MethyLight and immunohistochemistry were carried out to determine p16(INK4A) methylation and protein expression. RESULTS gamma-Tubulin protein expression was concordant with gene amplification; both of them were found to increase with atypical ductal hyperplasia-carcinoma sequence. The median value and positive rate of p16(INK4a) methylation increased while protein expression displayed a decreasing trend. P16(INK4a) methylation showed a firm association with gamma-tubulin gene amplification. CONCLUSION gamma-Tubulin gene amplification and the concomitant protein overexpression present not only in invasive carcinoma but also in a significant fraction of atypical hyperplasia and in situ carcinomas. P16(INK4a) methylation and gamma-tubulin gene amplification had a synergistic effect on tumor progression. The synergism might arise as a result of the combined influence that p16(INK4a) and gamma-tubulin have on the G1-S cell cycle checkpoints and centrosome.
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Affiliation(s)
- T Liu
- Breast Cancer Research Key Laboratory of National Education Ministry, Cancer Institute and Hospital, Tianjin Medical University, Tianjin, China
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30
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gammaTub23C interacts genetically with brahma chromatin-remodeling complexes in Drosophila melanogaster. Genetics 2008; 180:835-43. [PMID: 18780727 DOI: 10.1534/genetics.108.093492] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The brahma gene encodes the catalytic subunit of the Drosophila melanogaster BRM chromatin-remodeling complexes. Screening for mutations that interact with brahma, we isolated the dominant-negative Pearl-2 allele of gammaTub23C. gammaTub23C encodes one of the two gamma-tubulin isoforms in Drosophila and is essential for zygotic viability and normal adult patterning. gamma-Tubulin is a subunit of microtubule organizer complexes. We show that mutations in lethal (1) discs degenerate 4, which encodes the Grip91 subunit of microtubule organizer complexes, suppress the recessive lethality and the imaginal phenotypes caused by gammaTub23C mutations. The genetic interactions between gammaTub23C and chromatin-remodeling mutations suggest that gamma-tubulin might have a role in regulating gene expression.
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31
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Rogers GC, Rusan NM, Peifer M, Rogers SL. A multicomponent assembly pathway contributes to the formation of acentrosomal microtubule arrays in interphase Drosophila cells. Mol Biol Cell 2008; 19:3163-78. [PMID: 18463166 DOI: 10.1091/mbc.e07-10-1069] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
In animal cells, centrosomes nucleate microtubules that form polarized arrays to organize the cytoplasm. Drosophila presents an interesting paradox however, as centrosome-deficient mutant animals develop into viable adults. To understand this discrepancy, we analyzed behaviors of centrosomes and microtubules in Drosophila cells, in culture and in vivo, using a combination of live-cell imaging, electron microscopy, and RNAi. The canonical model of the cycle of centrosome function in animal cells states that centrosomes act as microtubule-organizing centers throughout the cell cycle. Unexpectedly, we found that many Drosophila cell-types display an altered cycle, in which functional centrosomes are only present during cell division. On mitotic exit, centrosomes disassemble producing interphase cells containing centrioles that lack microtubule-nucleating activity. Furthermore, steady-state interphase microtubule levels are not changed by codepleting both gamma-tubulins. However, gamma-tubulin RNAi delays microtubule regrowth after depolymerization, suggesting that it may function partially redundantly with another pathway. Therefore, we examined additional microtubule nucleating factors and found that Mini-spindles, CLIP-190, EB1, or dynein RNAi also delayed microtubule regrowth; surprisingly, this was not further prolonged when we codepleted gamma-tubulins. Taken together, these results modify our view of the cycle of centrosome function and reveal a multi-component acentrosomal microtubule assembly pathway to establish interphase microtubule arrays in Drosophila.
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Affiliation(s)
- Gregory C Rogers
- Department of Biology, Lineberger Comprehensive Cancer Center, and Carolina Center for Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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32
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Wiese C. Distinct Dgrip84 isoforms correlate with distinct gamma-tubulins in Drosophila. Mol Biol Cell 2007; 19:368-77. [PMID: 18003974 DOI: 10.1091/mbc.e07-08-0801] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Gamma-tubulin is an indispensable component of the animal centrosome and is required for proper microtubule organization. Within the cell, gamma-tubulin exists in a multiprotein complex containing between two (some yeasts) and six or more (metazoa) additional highly conserved proteins named gamma ring proteins (Grips) or gamma complex proteins (GCPs). gamma-Tubulin containing complexes isolated from Xenopus eggs or Drosophila embryos appear ring-shaped and have therefore been named the gamma-tubulin ring complex (gammaTuRC). Curiously, many organisms (including humans) have two distinct gamma-tubulin genes. In Drosophila, where the two gamma-tubulin isotypes have been studied most extensively, the gamma-tubulin genes are developmentally regulated: the "maternal" gamma-tubulin isotype (named gammaTub37CD according to its location on the genetic map) is expressed in the ovary and is deposited in the egg, where it is thought to orchestrate the meiotic and early embryonic cleavages. The second gamma-tubulin isotype (gammaTub23C) is ubiquitously expressed and persists in most of the cells of the adult fly. In those rare cases where both gamma-tubulins coexist in the same cell, they show distinct subcellular distributions and cell-cycle-dependent changes: gammaTub37CD mainly localizes to the centrosome, where its levels vary only slightly with the cell cycle. In contrast, the level of gammaTub23C at the centrosome increases at the beginning of mitosis, and gammaTub23C also associates with spindle pole microtubules. Here, we show that gammaTub23C forms discrete complexes that closely resemble the complexes formed by gammaTub37CD. Surprisingly, however, gammaTub23C associates with a distinct, longer splice variant of Dgrip84. This may reflect a role for Dgrip84 in regulating the activity and/or the location of the gamma-tubulin complexes formed with gammaTub37CD and gammaTub23C.
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Affiliation(s)
- Christiane Wiese
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA.
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Zhang J, Megraw TL. Proper recruitment of gamma-tubulin and D-TACC/Msps to embryonic Drosophila centrosomes requires Centrosomin Motif 1. Mol Biol Cell 2007; 18:4037-49. [PMID: 17671162 PMCID: PMC1995719 DOI: 10.1091/mbc.e07-05-0474] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Centrosomes are microtubule-organizing centers and play a dominant role in assembly of the microtubule spindle apparatus at mitosis. Although the individual binding steps in centrosome maturation are largely unknown, Centrosomin (Cnn) is an essential mitotic centrosome component required for assembly of all other known pericentriolar matrix (PCM) proteins to achieve microtubule-organizing activity at mitosis in Drosophila. We have identified a conserved motif (Motif 1) near the amino terminus of Cnn that is essential for its function in vivo. Cnn Motif 1 is necessary for proper recruitment of gamma-tubulin, D-TACC (the homolog of vertebrate transforming acidic coiled-coil proteins [TACC]), and Minispindles (Msps) to embryonic centrosomes but is not required for assembly of other centrosome components including Aurora A kinase and CP60. Centrosome separation and centrosomal satellite formation are severely disrupted in Cnn Motif 1 mutant embryos. However, actin organization into pseudocleavage furrows, though aberrant, remains partially intact. These data show that Motif 1 is necessary for some but not all of the activities conferred on centrosome function by intact Cnn.
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Affiliation(s)
- Jiuli Zhang
- Department of Pharmacology and The Cecil and Ida Green Center for Reproductive Biology Sciences, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9051
| | - Timothy L. Megraw
- Department of Pharmacology and The Cecil and Ida Green Center for Reproductive Biology Sciences, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9051
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34
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Taylor SS, Hardwick KG, Sawin KE, Biggins S, Piatti S, Khodjakov A, Rieder CL, Salmon ED, Musacchio A. Comment on "A centrosome-independent role for gamma-TuRC proteins in the spindle assembly checkpoint". Science 2007; 316:982; author reply 982. [PMID: 17510347 PMCID: PMC2590763 DOI: 10.1126/science.1139484] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Müller et al. (Reports, 27 October 2006, p. 654) showed that inhibition of the gamma-tubulin ring complex (gamma-TuRC) activates the spindle assembly checkpoint (SAC), which led them to suggest that gamma-TuRC proteins play molecular roles in SAC activation. Because gamma-TuRC inhibition leads to pleiotropic spindle defects, which are well known to activate kinetochore-derived checkpoint signaling, we believe that this conclusion is premature.
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Affiliation(s)
- Stephen S. Taylor
- Faculty of Life Sciences, University of Manchester, Manchester, UK
- To whom correspondence should be addressed. E-mail: (S.S.T.); (A.M.)
| | - Kevin G. Hardwick
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Kenneth E. Sawin
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Sue Biggins
- Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Simonetta Piatti
- Department of Biotechnology and Bioscience, University of Milan-Bicocca, Milan, Italy
| | - Alexey Khodjakov
- Division of Molecular Medicine, Wadsworth Center, New York State Department of Health, Albany, New York, USA
| | - Conly L. Rieder
- Division of Molecular Medicine, Wadsworth Center, New York State Department of Health, Albany, New York, USA
| | - Edward D. Salmon
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Andrea Musacchio
- Department of Experimental Oncology, European Institute of Oncology, Milan, Italy
- To whom correspondence should be addressed. E-mail: (S.S.T.); (A.M.)
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35
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Minakhina S, Druzhinina M, Steward R. Zfrp8, the Drosophila ortholog of PDCD2, functions in lymph gland development and controls cell proliferation. Development 2007; 134:2387-96. [PMID: 17522156 DOI: 10.1242/dev.003616] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We have identified a new gene, Zfrp8, as being essential for hematopoiesis in Drosophila. Zfrp8 (Zinc finger protein RP-8) is the Drosophila ortholog of the PDCD2 (programmed cell death 2) protein of unknown function, and is highly conserved in all eukaryotes. Zfrp8 mutants present a developmental delay, lethality during larval and pupal stages and hyperplasia of the hematopoietic organ, the lymph gland. This overgrowth results from an increase in proliferation of undifferentiated hemocytes throughout development and is accompanied by abnormal differentiation of hemocytes. Furthermore, the subcellular distribution of gamma-Tubulin and Cyclin B is affected. Consistent with this, the phenotype of the lymph gland of Zfpr8 heterozygous mutants is dominantly enhanced by the l(1)dd4 gene encoding Dgrip91, which is involved in anchoring gamma-Tubulin to the centrosome. The overgrowth phenotype is also enhanced by a mutation in Cdc27, which encodes a component of the anaphase-promoting complex (APC) that regulates the degradation of cyclins. No evidence for an apoptotic function of Zfrp8 was found. Based on the phenotype, genetic interactions and subcellular localization of Zfrp8, we propose that the protein is involved in the regulation of cell proliferation from embryonic stages onward, through the function of the centrosome, and regulates the level and localization of cell-cycle components. The overproliferation of cells in the lymph gland results in abnormal hemocyte differentiation.
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Affiliation(s)
- Svetlana Minakhina
- Waksman Institute, Department of Molecular Biology and Biochemistry, Cancer Institute of New Jersey, Rutgers University, 190 Frelinghuysen Road, Piscataway, NJ 08854-8020, USA
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36
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Müller H, Fogeron ML, Lehmann V, Lehrach H, Lange BMH. Response to Comments on "A Centrosome-Independent Role for γ-TuRC Proteins in the Spindle Assembly Checkpoint". Science 2007. [DOI: 10.1126/science.1136935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Weaver and Cleveland and Taylor
et al
. contend that our data on the involvement of the γ-tubulin ring complex (γ-TuRC) in the spindle assembly checkpoint (SAC) can be fully explained by kinetochore-derived checkpoint signaling. We maintain that (i) the interactions of γ-TuRC with Cdc20 and BubR1, and (ii) the activation of SAC by γ-TuRC depletion, in addition to the abrogation of kinetochore-microtubule interactions, argue for a more complex mechanism of SAC signaling.
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Affiliation(s)
- Hannah Müller
- Department of Vertebrate Genomics, Max-Planck Institute for Molecular Genetics, Ihnestrasse 73, D-14195 Berlin, Germany
| | - Marie-Laure Fogeron
- Department of Vertebrate Genomics, Max-Planck Institute for Molecular Genetics, Ihnestrasse 73, D-14195 Berlin, Germany
| | - Verena Lehmann
- Department of Vertebrate Genomics, Max-Planck Institute for Molecular Genetics, Ihnestrasse 73, D-14195 Berlin, Germany
| | - Hans Lehrach
- Department of Vertebrate Genomics, Max-Planck Institute for Molecular Genetics, Ihnestrasse 73, D-14195 Berlin, Germany
| | - Bodo M. H. Lange
- Department of Vertebrate Genomics, Max-Planck Institute for Molecular Genetics, Ihnestrasse 73, D-14195 Berlin, Germany
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37
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Raynaud-Messina B, Merdes A. γ-tubulin complexes and microtubule organization. Curr Opin Cell Biol 2007; 19:24-30. [PMID: 17178454 DOI: 10.1016/j.ceb.2006.12.008] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Accepted: 12/08/2006] [Indexed: 11/18/2022]
Abstract
Microtubule nucleation requires gamma-tubulin, which exists in two main protein complexes: the gamma-tubulin small complex, and the gamma-tubulin ring complex. During mitosis, these complexes accumulate at the centrosome to support spindle formation. Gamma-tubulin complexes are also present at non-centrosomal microtubule nucleation sites, both in interphase and in mitosis. In interphase, non-centrosomal nucleation enables the formation of microtubule bundles or networks of branched microtubules. Gamma-tubulin complexes may be involved not only in microtubule nucleation, but also in regulating microtubule dynamics. Recent findings indicate that the dynamics of microtubule plus-ends are altered, depending on the expression of gamma-tubulin complex proteins.
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Affiliation(s)
- Brigitte Raynaud-Messina
- Centre National de la Recherche Scientifique/Pierre Fabre, UMR 2587, 3 rue des Satellites, 31400 Toulouse, France
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Müller H, Fogeron ML, Lehmann V, Lehrach H, Lange BMH. A centrosome-independent role for gamma-TuRC proteins in the spindle assembly checkpoint. Science 2006; 314:654-7. [PMID: 17068266 DOI: 10.1126/science.1132834] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The spindle assembly checkpoint guards the fidelity of chromosome segregation. It requires the close cooperation of cell cycle regulatory proteins and cytoskeletal elements to sense spindle integrity. The role of the centrosome, the organizing center of the microtubule cytoskeleton, in the spindle checkpoint is unclear. We found that the molecular requirements for a functional spindle checkpoint included components of the large gamma-tubulin ring complex (gamma-TuRC). However, their localization at the centrosome and centrosome integrity were not essential for this function. Thus, the spindle checkpoint can be activated at the level of microtubule nucleation.
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Affiliation(s)
- Hannah Müller
- Department of Vertebrate Genomics, Max-Planck Institute for Molecular Genetics, Ihnestrasse 73, D-14195 Berlin, Germany
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Vogt N, Koch I, Schwarz H, Schnorrer F, Nüsslein-Volhard C. The gammaTuRC components Grip75 and Grip128 have an essential microtubule-anchoring function in the Drosophila germline. Development 2006; 133:3963-72. [PMID: 16971473 DOI: 10.1242/dev.02570] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The gamma-tubulin ring complex (gammaTuRC) forms an essential template for microtubule nucleation in animal cells. The molecular composition of the gammaTuRC has been described; however, the functions of the subunits proposed to form the cap structure remain to be characterized in vivo. In Drosophila, the core components of the gammaTuRC are essential for mitosis, whereas the cap component Grip75 is not required for viability but functions in bicoid RNA localization during oogenesis. The other cap components have not been analyzed in vivo. We report the functional characterization of the cap components Grip128 and Grip75. Animals with mutations in Dgrip128 or Dgrip75 are viable, but both males and females are sterile. Both proteins are required for the formation of distinct sets of microtubules, which facilitate bicoid RNA localization during oogenesis, the formation of the central microtubule aster connecting the meiosis II spindles in oocytes and cytokinesis in male meiosis. Grip75 and Grip128 anchor the axoneme at the nucleus during sperm elongation. We propose that Grip75 and Grip128 are required to tether microtubules at specific microtubule-organizing centers, instead of being required for general microtubule nucleation. The gammaTuRC cap structure may be essential only for non-centrosome-based microtubule functions.
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Affiliation(s)
- Nina Vogt
- Max-Planck-Institute for Developmental Biology, Department of Genetics, Spemannstr. 35, 72076 Tübingen, Germany.
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Vérollet C, Colombié N, Daubon T, Bourbon HM, Wright M, Raynaud-Messina B. Drosophila melanogaster gamma-TuRC is dispensable for targeting gamma-tubulin to the centrosome and microtubule nucleation. ACTA ACUST UNITED AC 2006; 172:517-28. [PMID: 16476773 PMCID: PMC2063672 DOI: 10.1083/jcb.200511071] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In metazoans, γ-tubulin acts within two main complexes, γ-tubulin small complexes (γ-TuSCs) and γ-tubulin ring complexes (γ-TuRCs). In higher eukaryotes, it is assumed that microtubule nucleation at the centrosome depends on γ-TuRCs, but the role of γ-TuRC components remains undefined. For the first time, we analyzed the function of all four γ-TuRC–specific subunits in Drosophila melanogaster: Dgrip75, Dgrip128, Dgrip163, and Dgp71WD. Grip-motif proteins, but not Dgp71WD, appear to be required for γ-TuRC assembly. Individual depletion of γ-TuRC components, in cultured cells and in vivo, induces mitotic delay and abnormal spindles. Surprisingly, γ-TuSCs are recruited to the centrosomes. These defects are less severe than those resulting from the inhibition of γ-TuSC components and do not appear critical for viability. Simultaneous cosilencing of all γ-TuRC proteins leads to stronger phenotypes and partial recruitment of γ-TuSC. In conclusion, γ-TuRCs are required for assembly of fully functional spindles, but we suggest that γ-TuSC could be targeted to the centrosomes, which is where basic microtubule assembly activities are maintained.
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Affiliation(s)
- Christel Vérollet
- Centre de Recherche en Pharmacologie, Santé, UMR 2587, Centre National de la Recherche Scientifique-Pierre Fabre, Institut de Sciences et Technologies du Médicament de Toulouse, 31432 Toulouse, Cedex 4, France
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