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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Serna M, Zimmermann F, Vineethakumari C, Gonzalez-Rodriguez N, Llorca O, Lüders J. CDK5RAP2 activates microtubule nucleator γTuRC by facilitating template formation and actin release. Dev Cell 2024:S1534-5807(24)00529-X. [PMID: 39321809 DOI: 10.1016/j.devcel.2024.09.001] [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: 02/22/2024] [Revised: 05/22/2024] [Accepted: 09/03/2024] [Indexed: 09/27/2024]
Abstract
To organize microtubules, cells tightly control the activity of the microtubule nucleator γ-tubulin ring complex (γTuRC). The open ring-shaped γTuRC was proposed to nucleate microtubules by a template mechanism. However, its splayed structure does not match microtubule symmetry, leaving it unclear how γTuRC becomes an efficient nucleator. Here, we identify the mechanism of γTuRC activation by CDK5RAP2 centrosomin motif 1 (CM1). Using cryoelectron microscopy (cryo-EM), we find that activation involves binding of multiple CM1 dimers to five distinct sites around the outside of the γTuRC cone, which crucially depends on regulatory modules formed by MZT2 and the N-terminal extensions of GCP2 subunits. CM1 binding promotes lateral interactions between GCP subunits to facilitate microtubule-like conformations and release of luminal actin that is integral to non-activated γTuRC. We propose a model where generation of γTuRC with an expanded conformational range, rather than perfect symmetry, is sufficient to boost nucleation activity.
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Affiliation(s)
- Marina Serna
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain
| | - Fabian Zimmermann
- Mechanisms of Disease Programme, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028 Barcelona, Spain
| | - Chithran Vineethakumari
- Mechanisms of Disease Programme, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028 Barcelona, Spain
| | - Nayim Gonzalez-Rodriguez
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain
| | - Oscar Llorca
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain.
| | - Jens Lüders
- Mechanisms of Disease Programme, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028 Barcelona, Spain.
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3
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Robichaud JH, Zhang Y, Chen C, He K, Huang Y, Zhang X, Sun X, Ma X, Hardyman G, Morrison CG, Dong Z, LeBrasseur NK, Ling K, Hu J. Transiently formed nucleus-to-cilium microtubule arrays mediate senescence initiation in a KIFC3-dependent manner. Nat Commun 2024; 15:7977. [PMID: 39266565 PMCID: PMC11393428 DOI: 10.1038/s41467-024-52363-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 09/04/2024] [Indexed: 09/14/2024] Open
Abstract
Despite the importance of cellular senescence in human health, how damaged cells undergo senescence remains elusive. We have previously shown that promyelocytic leukemia nuclear body (PML-NBs) translocation of the ciliary FBF1 is essential for senescence induction in stressed cells. Here we discover that an early cellular event occurring in stressed cells is the transient assembly of stress-induced nucleus-to-cilium microtubule arrays (sinc-MTs). The sinc-MTs are distinguished by unusual polyglutamylation and unique polarity, with minus-ends nucleating near the nuclear envelope and plus-ends near the ciliary base. KIFC3, a minus-end-directed kinesin, is recruited to plus-ends of sinc-MTs and interacts with the centrosomal protein CENEXIN1. In damaged cells, CENEXIN1 co-translocates with FBF1 to PML-NBs. Deficiency of KIFC3 abolishes PML-NB translocation of FBF1 and CENEXIN1, as well as senescence initiation in damaged cells. Our study reveals that KIFC3-mediated nuclear transport of FBF1 along polyglutamylated sinc-MTs is a prerequisite for senescence induction in mammalian cells.
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Affiliation(s)
- Jielu Hao Robichaud
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Yingyi Zhang
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Chuan Chen
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Kai He
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Yan Huang
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Xu Zhang
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
- Mayo Clinic Robert and Arlene Kogod Center on Aging, Mayo Clinic, Rochester, MN, USA
| | - Xiaobo Sun
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Xiaoyu Ma
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Gary Hardyman
- School of Biological Sciences, Institute for Global Food Security (IGFS), Queen's University Belfast, Belfast, Ireland
| | - Ciaran G Morrison
- Centre for Chromosome Biology, School of Biological and Chemical Sciences, University of Galway, Galway, Ireland
| | - Zheng Dong
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, USA
- Research Department, Charlie Norwood VA Medical Center, Augusta, GA, USA
| | - Nathan K LeBrasseur
- Mayo Clinic Robert and Arlene Kogod Center on Aging, Mayo Clinic, Rochester, MN, USA
- Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, MN, USA
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
| | - Kun Ling
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Jinghua Hu
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA.
- Mayo Clinic Robert M. and Billie Kelley Pirnie Translational Polycystic Kidney Disease Center, Mayo Clinic, Rochester, MN, USA.
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA.
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4
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Gao Q, Vermeulen BJA, Würtz M, Shin H, Erdogdu D, Zheng A, Hofer FW, Neuner A, Pfeffer S, Schiebel E. The structure of the γ-TuRC at the microtubule minus end - not just one solution. Bioessays 2024; 46:e2400117. [PMID: 39044599 DOI: 10.1002/bies.202400117] [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: 05/20/2024] [Revised: 07/09/2024] [Accepted: 07/11/2024] [Indexed: 07/25/2024]
Abstract
In cells, microtubules (MTs) assemble from α/β-tubulin subunits at nucleation sites containing the γ-tubulin ring complex (γ-TuRC). Within the γ-TuRC, exposed γ-tubulin molecules act as templates for MT assembly by interacting with α/β-tubulin. The vertebrate γ-TuRC is scaffolded by γ-tubulin-interacting proteins GCP2-6 arranged in a specific order. Interestingly, the γ-tubulin molecules in the γ-TuRC deviate from the cylindrical geometry of MTs, raising the question of how the γ-TuRC structure changes during MT nucleation. Recent studies on the structure of the vertebrate γ-TuRC attached to the end of MTs came to varying conclusions. In vitro assembly of MTs, facilitated by an α-tubulin mutant, resulted in a closed, cylindrical γ-TuRC showing canonical interactions between all γ-tubulin molecules and α/β-tubulin subunits. Conversely, native MTs formed in a frog extract were capped by a partially closed γ-TuRC, with some γ-tubulin molecules failing to align with α/β-tubulin. This review discusses these outcomes, along with the broader implications.
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Affiliation(s)
- Qi Gao
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Bram J A Vermeulen
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Martin Würtz
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Hyesu Shin
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Dilara Erdogdu
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Anjun Zheng
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Florian W Hofer
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Annett Neuner
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Stefan Pfeffer
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
| | - Elmar Schiebel
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Heidelberg, Germany
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5
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Thomas A, Meraldi P. Centrosome age breaks spindle size symmetry even in cells thought to divide symmetrically. J Cell Biol 2024; 223:e202311153. [PMID: 39012627 PMCID: PMC11252449 DOI: 10.1083/jcb.202311153] [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: 11/27/2023] [Revised: 03/14/2024] [Accepted: 05/03/2024] [Indexed: 07/17/2024] Open
Abstract
Centrosomes are the main microtubule-organizing centers in animal cells. Due to the semiconservative nature of centrosome duplication, the two centrosomes differ in age. In asymmetric stem cell divisions, centrosome age can induce an asymmetry in half-spindle lengths. However, whether centrosome age affects the symmetry of the two half-spindles in tissue culture cells thought to divide symmetrically is unknown. Here, we show that in human epithelial and fibroblastic cell lines centrosome age imposes a mild spindle asymmetry that leads to asymmetric cell daughter sizes. At the mechanistic level, we show that this asymmetry depends on a cenexin-bound pool of the mitotic kinase Plk1, which favors the preferential accumulation on old centrosomes of the microtubule nucleation-organizing proteins pericentrin, γ-tubulin, and Cdk5Rap2, and microtubule regulators TPX2 and ch-TOG. Consistently, we find that old centrosomes have a higher microtubule nucleation capacity. We postulate that centrosome age breaks spindle size symmetry via microtubule nucleation even in cells thought to divide symmetrically.
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Affiliation(s)
- Alexandre Thomas
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
- Translational Research Centre in Onco-hematology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Patrick Meraldi
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, Geneva, Switzerland
- Translational Research Centre in Onco-hematology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
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6
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Aher A, Urnavicius L, Xue A, Neselu K, Kapoor TM. Structure of the γ-tubulin ring complex-capped microtubule. Nat Struct Mol Biol 2024; 31:1124-1133. [PMID: 38609661 PMCID: PMC11257807 DOI: 10.1038/s41594-024-01264-z] [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: 12/01/2023] [Accepted: 03/04/2024] [Indexed: 04/14/2024]
Abstract
Microtubules are composed of α-tubulin and β-tubulin dimers positioned head-to-tail to form protofilaments that associate laterally in varying numbers. It is not known how cellular microtubules assemble with the canonical 13-protofilament architecture, resulting in micrometer-scale α/β-tubulin tracks for intracellular transport that align with, rather than spiral along, the long axis of the filament. We report that the human ~2.3 MDa γ-tubulin ring complex (γ-TuRC), an essential regulator of microtubule formation that contains 14 γ-tubulins, selectively nucleates 13-protofilament microtubules. Cryogenic electron microscopy reconstructions of γ-TuRC-capped microtubule minus ends reveal the extensive intra-domain and inter-domain motions of γ-TuRC subunits that accommodate luminal bridge components and establish lateral and longitudinal interactions between γ-tubulins and α-tubulins. Our structures suggest that γ-TuRC, an inefficient nucleation template owing to its splayed conformation, can transform into a compacted cap at the microtubule minus end and set the lattice architecture of cellular microtubules.
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Affiliation(s)
- Amol Aher
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY, USA
| | - Linas Urnavicius
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY, USA
| | - Allen Xue
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY, USA
| | - Kasahun Neselu
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
| | - Tarun M Kapoor
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY, USA.
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7
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Vermeulen BJ, Böhler A, Gao Q, Neuner A, Župa E, Chu Z, Würtz M, Jäkle U, Gruss OJ, Pfeffer S, Schiebel E. γ-TuRC asymmetry induces local protofilament mismatch at the RanGTP-stimulated microtubule minus end. EMBO J 2024; 43:2062-2085. [PMID: 38600243 PMCID: PMC11099078 DOI: 10.1038/s44318-024-00087-4] [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: 11/03/2023] [Revised: 03/15/2024] [Accepted: 03/18/2024] [Indexed: 04/12/2024] Open
Abstract
The γ-tubulin ring complex (γ-TuRC) is a structural template for de novo microtubule assembly from α/β-tubulin units. The isolated vertebrate γ-TuRC assumes an asymmetric, open structure deviating from microtubule geometry, suggesting that γ-TuRC closure may underlie regulation of microtubule nucleation. Here, we isolate native γ-TuRC-capped microtubules from Xenopus laevis egg extract nucleated through the RanGTP-induced pathway for spindle assembly and determine their cryo-EM structure. Intriguingly, the microtubule minus end-bound γ-TuRC is only partially closed and consequently, the emanating microtubule is locally misaligned with the γ-TuRC and asymmetric. In the partially closed conformation of the γ-TuRC, the actin-containing lumenal bridge is locally destabilised, suggesting lumenal bridge modulation in microtubule nucleation. The microtubule-binding protein CAMSAP2 specifically binds the minus end of γ-TuRC-capped microtubules, indicating that the asymmetric minus end structure may underlie recruitment of microtubule-modulating factors for γ-TuRC release. Collectively, we reveal a surprisingly asymmetric microtubule minus end protofilament organisation diverging from the regular microtubule structure, with direct implications for the kinetics and regulation of nucleation and subsequent modulation of microtubules during spindle assembly.
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Affiliation(s)
- Bram Ja Vermeulen
- Zentrum für Molekulare Biologie, Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Anna Böhler
- Zentrum für Molekulare Biologie, Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Qi Gao
- Zentrum für Molekulare Biologie, Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Annett Neuner
- Zentrum für Molekulare Biologie, Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Erik Župa
- Zentrum für Molekulare Biologie, Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Zhenzhen Chu
- Institut für Genetik, Universität Bonn, Bonn, Germany
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education, Beijing), Lymphoma Department, Peking University Cancer Hospital & Institute, Beijing, China
| | - Martin Würtz
- Zentrum für Molekulare Biologie, Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Ursula Jäkle
- Zentrum für Molekulare Biologie, Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | | | - Stefan Pfeffer
- Zentrum für Molekulare Biologie, Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany.
| | - Elmar Schiebel
- Zentrum für Molekulare Biologie, Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany.
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8
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Rai D, Song Y, Hua S, Stecker K, Monster JL, Yin V, Stucchi R, Xu Y, Zhang Y, Chen F, Katrukha EA, Altelaar M, Heck AJR, Wieczorek M, Jiang K, Akhmanova A. CAMSAPs and nucleation-promoting factors control microtubule release from γ-TuRC. Nat Cell Biol 2024; 26:404-420. [PMID: 38424271 PMCID: PMC10940162 DOI: 10.1038/s41556-024-01366-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 01/26/2024] [Indexed: 03/02/2024]
Abstract
γ-Tubulin ring complex (γ-TuRC) is the major microtubule-nucleating factor. After nucleation, microtubules can be released from γ-TuRC and stabilized by other proteins, such as CAMSAPs, but the biochemical cross-talk between minus-end regulation pathways is poorly understood. Here we reconstituted this process in vitro using purified components. We found that all CAMSAPs could bind to the minus ends of γ-TuRC-attached microtubules. CAMSAP2 and CAMSAP3, which decorate and stabilize growing minus ends but not the minus-end tracking protein CAMSAP1, induced microtubule release from γ-TuRC. CDK5RAP2, a γ-TuRC-interactor, and CLASP2, a regulator of microtubule growth, strongly stimulated γ-TuRC-dependent microtubule nucleation, but only CDK5RAP2 suppressed CAMSAP binding to γ-TuRC-anchored minus ends and their release. CDK5RAP2 also improved selectivity of γ-tubulin-containing complexes for 13- rather than 14-protofilament microtubules in microtubule-capping assays. Knockout and overexpression experiments in cells showed that CDK5RAP2 inhibits the formation of CAMSAP2-bound microtubules detached from the microtubule-organizing centre. We conclude that CAMSAPs can release newly nucleated microtubules from γ-TuRC, whereas nucleation-promoting factors can differentially regulate this process.
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Affiliation(s)
- Dipti Rai
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Yinlong Song
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Shasha Hua
- State Key Laboratory of Oral and Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School and Hospital of Stomatology, Medical Research Institute, Wuhan University, Wuhan, China
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China
| | - Kelly Stecker
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research, Utrecht Institute for Pharmaceutical Sciences and the Netherlands Proteomics Center, Utrecht University, Utrecht, the Netherlands
- Netherlands Proteomics Center, Utrecht, the Netherlands
| | - Jooske L Monster
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Victor Yin
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research, Utrecht Institute for Pharmaceutical Sciences and the Netherlands Proteomics Center, Utrecht University, Utrecht, the Netherlands
- Netherlands Proteomics Center, Utrecht, the Netherlands
| | - Riccardo Stucchi
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research, Utrecht Institute for Pharmaceutical Sciences and the Netherlands Proteomics Center, Utrecht University, Utrecht, the Netherlands
- Netherlands Proteomics Center, Utrecht, the Netherlands
| | - Yixin Xu
- Department of Biology, Institute of Molecular Biology & Biophysics, ETH Zürich, Zurich, Switzerland
| | - Yaqian Zhang
- State Key Laboratory of Oral and Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School and Hospital of Stomatology, Medical Research Institute, Wuhan University, Wuhan, China
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China
| | - Fangrui Chen
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Eugene A Katrukha
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Maarten Altelaar
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research, Utrecht Institute for Pharmaceutical Sciences and the Netherlands Proteomics Center, Utrecht University, Utrecht, the Netherlands
- Netherlands Proteomics Center, Utrecht, the Netherlands
| | - Albert J R Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research, Utrecht Institute for Pharmaceutical Sciences and the Netherlands Proteomics Center, Utrecht University, Utrecht, the Netherlands
- Netherlands Proteomics Center, Utrecht, the Netherlands
| | - Michal Wieczorek
- Department of Biology, Institute of Molecular Biology & Biophysics, ETH Zürich, Zurich, Switzerland
| | - Kai Jiang
- State Key Laboratory of Oral and Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School and Hospital of Stomatology, Medical Research Institute, Wuhan University, Wuhan, China.
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China.
| | - Anna Akhmanova
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands.
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9
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Brito C, Serna M, Guerra P, Llorca O, Surrey T. Transition of human γ-tubulin ring complex into a closed conformation during microtubule nucleation. Science 2024; 383:870-876. [PMID: 38305685 DOI: 10.1126/science.adk6160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 01/22/2024] [Indexed: 02/03/2024]
Abstract
Microtubules are essential for intracellular organization and chromosome segregation. They are nucleated by the γ-tubulin ring complex (γTuRC). However, isolated vertebrate γTuRC adopts an open conformation that deviates from the microtubule structure, raising the question of the nucleation mechanism. In this study, we determined cryo-electron microscopy structures of human γTuRC bound to a nascent microtubule. Structural changes of the complex into a closed conformation ensure that γTuRC templates the 13-protofilament microtubules that exist in human cells. Closure is mediated by a latch that interacts with incorporating tubulin, making it part of the closing mechanism. Further rearrangements involve all γTuRC subunits and the removal of the actin-containing luminal bridge. Our proposed mechanism of microtubule nucleation by human γTuRC relies on large-scale structural changes that are likely the target of regulation in cells.
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Affiliation(s)
- Cláudia Brito
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Marina Serna
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Pablo Guerra
- Cryo-Electron Microscopy Platform-IBMB CSIC, Joint Electron Microscopy Center at ALBA (JEMCA), Barcelona, Spain
| | - Oscar Llorca
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Thomas Surrey
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
- Catalan Institution for Research and Advanced Studies (ICREA), Barcelona, Spain
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10
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Wong SS, Wainman A, Saurya S, Raff JW. Regulation of centrosome size by the cell-cycle oscillator in Drosophila embryos. EMBO J 2024; 43:414-436. [PMID: 38233576 PMCID: PMC10898259 DOI: 10.1038/s44318-023-00022-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 12/12/2023] [Accepted: 12/13/2023] [Indexed: 01/19/2024] Open
Abstract
Mitotic centrosomes assemble when centrioles recruit large amounts of pericentriolar material (PCM) around themselves. In early C. elegans embryos, mitotic centrosome size appears to be set by the limiting amount of a key component. In Drosophila syncytial embryos, thousands of mitotic centrosomes are assembled as the embryo proceeds through 13 rounds of rapid nuclear division, driven by a core cell cycle oscillator. These divisions slow during nuclear cycles 11-13, and we find that centrosomes respond by reciprocally decreasing their growth rate, but increasing their growth period-so that they grow to a relatively consistent size at each cycle. At the start of each cycle, moderate CCO activity initially promotes centrosome growth, in part by stimulating Polo/PLK1 recruitment to centrosomes. Later in each cycle, high CCO activity inhibits centrosome growth by suppressing the centrosomal recruitment and/or maintenance of centrosome proteins. Thus, in fly embryos, mitotic centrosome size appears to be regulated predominantly by the core cell cycle oscillator, rather than by the depletion of a limiting component.
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Affiliation(s)
- Siu-Shing Wong
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
| | - Alan Wainman
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
| | - Saroj Saurya
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
| | - Jordan W Raff
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK.
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11
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Romer B, Travis SM, Mahon BP, McManus CT, Jeffrey PD, Coudray N, Raghu R, Rale MJ, Zhong ED, Bhabha G, Petry S. Conformational states of the microtubule nucleator, the γ-tubulin ring complex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.19.572162. [PMID: 38187763 PMCID: PMC10769196 DOI: 10.1101/2023.12.19.572162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Microtubules (MTs) perform essential functions in the cell, and it is critical that they are made at the correct cellular location and cell cycle stage. This nucleation process is catalyzed by the γ-tubulin ring complex (γ-TuRC), a cone-shaped protein complex composed of over 30 subunits. Despite recent insight into the structure of vertebrate γ-TuRC, which shows that its diameter is wider than that of a MT, and that it exhibits little of the symmetry expected for an ideal MT template, the question of how γ-TuRC achieves MT nucleation remains open. Here, we utilized single particle cryo-EM to identify two conformations of γ-TuRC. The helix composed of 14 γ-tubulins at the top of the γ-TuRC cone undergoes substantial deformation, which is predominantly driven by bending of the hinge between the GRIP1 and GRIP2 domains of the γ-tubulin complex proteins. However, surprisingly, this deformation does not remove the inherent asymmetry of γ-TuRC. To further investigate the role of γ-TuRC conformational change, we used cryo electron-tomography (cryo-ET) to obtain a 3D reconstruction of γ-TuRC bound to a nucleated MT, providing insight into the post-nucleation state. Rigid-body fitting of our cryo-EM structures into this reconstruction suggests that the MT lattice is nucleated by spokes 2 through 14 of the γ-tubulin helix, which entails spokes 13 and 14 becoming more structured than what is observed in apo γ-TuRC. Together, our results allow us to propose a model for conformational changes in γ-TuRC and how these may facilitate MT formation in a cell.
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Affiliation(s)
- Brianna Romer
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Sophie M. Travis
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Brian P. Mahon
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
- Present address: Molecular Structure and Design, Bristol Myers Squibb, Princeton, NJ, USA
| | - Collin T. McManus
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Philip D. Jeffrey
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Nicolas Coudray
- Department of Cell Biology, NYU School of Medicine, New York City, NY, USA
- Applied Bioinformatics Laboratories, NYU School of Medicine, New York, NY, USA
| | - Rishwanth Raghu
- Department of Computer Science, Princeton University, Princeton, NJ, USA
| | - Michael J. Rale
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
- Present address: Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Ellen D. Zhong
- Department of Computer Science, Princeton University, Princeton, NJ, USA
| | - Gira Bhabha
- Department of Cell Biology, NYU School of Medicine, New York City, NY, USA
| | - Sabine Petry
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
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12
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Aher A, Urnavicius L, Xue A, Neselu K, Kapoor TM. Structure of the γ-tubulin ring complex-capped microtubule. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.20.567916. [PMID: 38045257 PMCID: PMC10690160 DOI: 10.1101/2023.11.20.567916] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Microtubules are composed of α/β-tubulin dimers positioned head-to-tail to form protofilaments that associate laterally in varying numbers. It is not known how cellular microtubules assemble with the canonical 13-protofilament architecture, resulting in micrometer-scale α/β-tubulin tracks for intracellular transport that align with, rather than spiral along, the filament's long-axis. We report that the human ∼2.3MDa γ-tubulin ring complex (γ-TuRC), an essential regulator of microtubule formation that contains 14 γ-tubulins, selectively nucleates 13-protofilament microtubules. Cryo-EM reconstructions of γ-TuRC-capped microtubule minus-ends reveal the extensive intra- and inter-domain motions of γ-TuRC subunits that accommodate its actin-containing luminal bridge and establish lateral and longitudinal interactions between γ- and α-tubulins. Our structures reveal how free γ-TuRC, an inefficient nucleation template due to its splayed conformation, transforms into a stable cap that blocks addition or loss of α/β-tubulins from minus-ends and sets the lattice architecture of cellular microtubules. One Sentence Summary Structural insights into how the γ-tubulin ring complex nucleates and caps a 13-protofilament microtubule.
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13
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Chen M, Xu L, Wu Y, Soba P, Hu C. The organization and function of the Golgi apparatus in dendrite development and neurological disorders. Genes Dis 2023; 10:2425-2442. [PMID: 37554209 PMCID: PMC10404969 DOI: 10.1016/j.gendis.2022.11.009] [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: 07/04/2022] [Revised: 09/13/2022] [Accepted: 11/05/2022] [Indexed: 12/24/2022] Open
Abstract
Dendrites are specialized neuronal compartments that sense, integrate and transfer information in the neural network. Their development is tightly controlled and abnormal dendrite morphogenesis is strongly linked to neurological disorders. While dendritic morphology ranges from relatively simple to extremely complex for a specified neuron, either requires a functional secretory pathway to continually replenish proteins and lipids to meet dendritic growth demands. The Golgi apparatus occupies the center of the secretory pathway and is regulating posttranslational modifications, sorting, transport, and signal transduction, as well as acting as a non-centrosomal microtubule organization center. The neuronal Golgi apparatus shares common features with Golgi in other eukaryotic cell types but also forms distinct structures known as Golgi outposts that specifically localize in dendrites. However, the organization and function of Golgi in dendrite development and its impact on neurological disorders is just emerging and so far lacks a systematic summary. We describe the organization of the Golgi apparatus in neurons, review the current understanding of Golgi function in dendritic morphogenesis, and discuss the current challenges and future directions.
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Affiliation(s)
- Meilan Chen
- Key Laboratory of Brain, Cognition and Education Sciences, Ministry of Education Institute for Brain, Science and Rehabilitation, South China Normal University, Guangzhou, Guangdong 510631, China
- Department of Ophthalmology, Guangdong Second Provincial General Hospital, Guangzhou, Guangdong 510320, China
| | - Lu Xu
- Key Laboratory of Brain, Cognition and Education Sciences, Ministry of Education Institute for Brain, Science and Rehabilitation, South China Normal University, Guangzhou, Guangdong 510631, China
| | - Yi Wu
- Department of Ophthalmology, Guangdong Second Provincial General Hospital, Guangzhou, Guangdong 510320, China
| | - Peter Soba
- LIMES Institute, Department of Molecular Brain Physiology and Behavior, University of Bonn, Bonn 53115, Germany
- Institute of Physiology and Pathophysiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen 91054, Germany
| | - Chun Hu
- Key Laboratory of Brain, Cognition and Education Sciences, Ministry of Education Institute for Brain, Science and Rehabilitation, South China Normal University, Guangzhou, Guangdong 510631, China
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14
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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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15
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Kraus J, Alfaro-Aco R, Gouveia B, Petry S. Microtubule nucleation for spindle assembly: one molecule at a time. Trends Biochem Sci 2023; 48:761-775. [PMID: 37482516 PMCID: PMC10789498 DOI: 10.1016/j.tibs.2023.06.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 06/01/2023] [Accepted: 06/06/2023] [Indexed: 07/25/2023]
Abstract
The cell orchestrates the dance of chromosome segregation with remarkable speed and fidelity. The mitotic spindle is built from scratch after interphase through microtubule (MT) nucleation, which is dependent on the γ-tubulin ring complex (γ-TuRC), the universal MT template. Although several MT nucleation pathways build the spindle framework, the question of when and how γ-TuRC is targeted to these nucleation sites in the spindle and subsequently activated remains an active area of investigation. Recent advances facilitated the discovery of new MT nucleation effectors and their mechanisms of action. In this review, we illuminate each spindle assembly pathway and subsequently consider how the pathways are merged to build a spindle.
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Affiliation(s)
- Jodi Kraus
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | | | - Bernardo Gouveia
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
| | - Sabine Petry
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA.
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16
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Valdez VA, Neahring L, Petry S, Dumont S. Mechanisms underlying spindle assembly and robustness. Nat Rev Mol Cell Biol 2023; 24:523-542. [PMID: 36977834 PMCID: PMC10642710 DOI: 10.1038/s41580-023-00584-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2023] [Indexed: 03/30/2023]
Abstract
The microtubule-based spindle orchestrates chromosome segregation during cell division. Following more than a century of study, many components and pathways contributing to spindle assembly have been described, but how the spindle robustly assembles remains incompletely understood. This process involves the self-organization of a large number of molecular parts - up to hundreds of thousands in vertebrate cells - whose local interactions give rise to a cellular-scale structure with emergent architecture, mechanics and function. In this Review, we discuss key concepts in our understanding of spindle assembly, focusing on recent advances and the new approaches that enabled them. We describe the pathways that generate the microtubule framework of the spindle by driving microtubule nucleation in a spatially controlled fashion and present recent insights regarding the organization of individual microtubules into structural modules. Finally, we discuss the emergent properties of the spindle that enable robust chromosome segregation.
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Affiliation(s)
| | - Lila Neahring
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA, USA
- Developmental & Stem Cell Biology Graduate Program, UCSF, San Francisco, CA, USA
| | - Sabine Petry
- Molecular Biology, Princeton University, Princeton, NJ, USA.
| | - Sophie Dumont
- Department of Bioengineering & Therapeutic Sciences, UCSF, San Francisco, CA, USA.
- Developmental & Stem Cell Biology Graduate Program, UCSF, San Francisco, CA, USA.
- Department of Biochemistry & Biophysics, UCSF, San Francisco, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
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17
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Farcy S, Hachour H, Bahi-Buisson N, Passemard S. Genetic Primary Microcephalies: When Centrosome Dysfunction Dictates Brain and Body Size. Cells 2023; 12:1807. [PMID: 37443841 PMCID: PMC10340463 DOI: 10.3390/cells12131807] [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: 04/06/2023] [Revised: 06/04/2023] [Accepted: 06/13/2023] [Indexed: 07/15/2023] Open
Abstract
Primary microcephalies (PMs) are defects in brain growth that are detectable at or before birth and are responsible for neurodevelopmental disorders. Most are caused by biallelic or, more rarely, dominant mutations in one of the likely hundreds of genes encoding PM proteins, i.e., ubiquitous centrosome or microtubule-associated proteins required for the division of neural progenitor cells in the embryonic brain. Here, we provide an overview of the different types of PMs, i.e., isolated PMs with or without malformations of cortical development and PMs associated with short stature (microcephalic dwarfism) or sensorineural disorders. We present an overview of the genetic, developmental, neurological, and cognitive aspects characterizing the most representative PMs. The analysis of phenotypic similarities and differences among patients has led scientists to elucidate the roles of these PM proteins in humans. Phenotypic similarities indicate possible redundant functions of a few of these proteins, such as ASPM and WDR62, which play roles only in determining brain size and structure. However, the protein pericentrin (PCNT) is equally required for determining brain and body size. Other PM proteins perform both functions, albeit to different degrees. Finally, by comparing phenotypes, we considered the interrelationships among these proteins.
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Affiliation(s)
- Sarah Farcy
- UMR144, Institut Curie, 75005 Paris, France;
- Inserm UMR-S 1163, Institut Imagine, 75015 Paris, France
| | - Hassina Hachour
- Service de Neurologie Pédiatrique, DMU INOV-RDB, APHP, Hôpital Robert Debré, 75019 Paris, France;
| | - Nadia Bahi-Buisson
- Service de Neurologie Pédiatrique, DMU MICADO, APHP, Hôpital Necker Enfants Malades, 75015 Paris, France;
- Université Paris Cité, Inserm UMR-S 1163, Institut Imagine, 75015 Paris, France
| | - Sandrine Passemard
- Service de Neurologie Pédiatrique, DMU INOV-RDB, APHP, Hôpital Robert Debré, 75019 Paris, France;
- Université Paris Cité, Inserm UMR 1141, NeuroDiderot, 75019 Paris, France
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18
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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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19
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Rajeev R, Mukhopadhyay S, Bhagyanath S, Devu Priya MRS, Manna TK. TACC3-ch-TOG interaction regulates spindle microtubule assembly by controlling centrosomal recruitment of γ-TuRC. Biosci Rep 2023; 43:232568. [PMID: 36790370 PMCID: PMC10037420 DOI: 10.1042/bsr20221882] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 02/07/2023] [Accepted: 02/14/2023] [Indexed: 02/16/2023] Open
Abstract
γ-Tubulin ring complex (γ-TuRC), composed of γ-tubulin and multiple γ-tubulin complex proteins (GCPs), serves as the major microtubule nucleating complex in animal cells. However, several γ-TuRC-associated proteins have been shown to control its function. Centrosomal adaptor protein, TACC3, is one such γ-TuRC-interacting factor that is essential for proper mitotic spindle assembly across organisms. ch-TOG is another microtubule assembly promoting protein, which interacts with TACC3 and cooperates in mitotic spindle assembly. However, the mechanism how TACC3-ch-TOG interaction regulates microtubule assembly and the γ-TuRC functions at the centrosomes remain unclear. Here, we show that deletion of the ch-TOG-binding region in TACC3 enhances recruitment of the γ-TuRC proteins to centrosomes and aggravates spindle microtubule assembly in human cells. Loss of TACC3-ch-TOG binding imparts stabilization on TACC3 interaction with the γ-TuRC proteins and it does so by stimulating TACC3 phosphorylation and thereby enhancing phospho-TACC3 recruitment to the centrosomes. We also show that localization of ch-TOG at the centrosomes is substantially reduced and the same on the spindle microtubules is increased in its TACC3-unbound condition. Additional results reveal that ch-TOG depletion stimulates γ-tubulin localization on the spindles without significantly affecting the centrosomal γ-tubulin level. The results indicate that ch-TOG binding to TACC3 controls TACC3 phosphorylation and TACC3-mediated stabilization of the γ-TuRCs at the centrosomes. They also implicate that the spatio-temporal control of TACC3 phosphorylation via ch-TOG-binding ensures mitotic spindle assembly to the optimal level.
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Affiliation(s)
- Resmi Rajeev
- School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram 695551, India
| | - Swarnendu Mukhopadhyay
- School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram 695551, India
| | - Suresh Bhagyanath
- School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram 695551, India
| | - Manu Rani S Devu Priya
- School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram 695551, India
| | - Tapas K Manna
- School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram 695551, India
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20
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Wu J, Larreategui-Aparicio A, Lambers MLA, Bodor DL, Klaasen SJ, Tollenaar E, de Ruijter-Villani M, Kops GJPL. Microtubule nucleation from the fibrous corona by LIC1-pericentrin promotes chromosome congression. Curr Biol 2023; 33:912-925.e6. [PMID: 36720222 PMCID: PMC10017265 DOI: 10.1016/j.cub.2023.01.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 11/17/2022] [Accepted: 01/06/2023] [Indexed: 01/31/2023]
Abstract
Error-free chromosome segregation in mitosis and meiosis relies on the assembly of a microtubule-based spindle that interacts with kinetochores to guide chromosomes to the cell equator before segregation in anaphase. Microtubules sprout from nucleation sites such as centrosomes, but kinetochores can also promote microtubule formation. It is unclear, however, how kinetochore-derived microtubules are generated and what their role is in chromosome segregation. Here, we show that the transient outer-kinetochore meshwork known as the fibrous corona serves as an autonomous microtubule nucleation platform. The fibrous corona is essential for the nucleation of kinetochore-derived microtubules, and when dissociated from the core kinetochore, it retains microtubule nucleation capacity. Nucleation relies on a fibrous-corona-bound pool of the LIC1 subunit of the dynein motor complex, which interacts with the γ-tubulin-tethering protein pericentrin (PCNT). PCNT is essential for microtubule nucleation from fibrous coronas, and in centrosome-depleted cells, where nearly all mitotic nucleation occurs at fibrous coronas, chromosome congression is fully dependent on PCNT. We further show that chromosomes in bovine oocytes, which naturally lack centrosomes, have highly expanded fibrous coronas that drive chromosome-derived microtubule nucleation. Preventing fibrous corona expansion in these cells impairs chromosome congression and causes spindle assembly defects. Our results show that fibrous coronas are autonomous microtubule-organizing centers that are important for spindle assembly, which may be especially relevant in acentrosomal cells such as oocytes.
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Affiliation(s)
- Jingchao Wu
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences (KNAW), Uppsalalaan 8, 3584CT Utrecht, the Netherlands; University Medical Center Utrecht, Heidelberglaan 100, 3584CX Utrecht, the Netherlands; Oncode Institute, Jaarbeursplein 6, 3521AL Utrecht, the Netherlands
| | - Ainhoa Larreategui-Aparicio
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences (KNAW), Uppsalalaan 8, 3584CT Utrecht, the Netherlands; University Medical Center Utrecht, Heidelberglaan 100, 3584CX Utrecht, the Netherlands; Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584CL Utrecht, the Netherlands
| | - Maaike L A Lambers
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences (KNAW), Uppsalalaan 8, 3584CT Utrecht, the Netherlands; University Medical Center Utrecht, Heidelberglaan 100, 3584CX Utrecht, the Netherlands; Oncode Institute, Jaarbeursplein 6, 3521AL Utrecht, the Netherlands
| | - Dani L Bodor
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences (KNAW), Uppsalalaan 8, 3584CT Utrecht, the Netherlands; University Medical Center Utrecht, Heidelberglaan 100, 3584CX Utrecht, the Netherlands; Oncode Institute, Jaarbeursplein 6, 3521AL Utrecht, the Netherlands
| | - Sjoerd J Klaasen
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences (KNAW), Uppsalalaan 8, 3584CT Utrecht, the Netherlands; University Medical Center Utrecht, Heidelberglaan 100, 3584CX Utrecht, the Netherlands; Oncode Institute, Jaarbeursplein 6, 3521AL Utrecht, the Netherlands
| | - Eveline Tollenaar
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584CL Utrecht, the Netherlands
| | - Marta de Ruijter-Villani
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences (KNAW), Uppsalalaan 8, 3584CT Utrecht, the Netherlands; University Medical Center Utrecht, Heidelberglaan 100, 3584CX Utrecht, the Netherlands; Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 1, 3584CL Utrecht, the Netherlands; Division of Woman and Baby, Department of Obstetrics and Gynecology, University Medical Centre Utrecht, Heidelberglaan 100, 3584CX Utrecht, the Netherlands
| | - Geert J P L Kops
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences (KNAW), Uppsalalaan 8, 3584CT Utrecht, the Netherlands; University Medical Center Utrecht, Heidelberglaan 100, 3584CX Utrecht, the Netherlands; Oncode Institute, Jaarbeursplein 6, 3521AL Utrecht, the Netherlands.
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21
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Shen Y, Chen Y, Lin Y, Li Y, Liu P, Zhang B, Wang Y, Chan KC, Mak NK, Kahn M, Qi RZ, Yang H. CDK5RAP2 is a Wnt target gene and promotes stemness and progression of oral squamous cell carcinoma. Cell Death Dis 2023; 14:107. [PMID: 36774351 PMCID: PMC9922250 DOI: 10.1038/s41419-023-05652-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 02/02/2023] [Accepted: 02/03/2023] [Indexed: 02/13/2023]
Abstract
In oral squamous cell carcinoma (OSCC), a highly aggressive and frequently lethal malignancy, the role and action mechanism of the microtubule regulatory protein CDK5RAP2 have not been fully understood. Here, we show that CDK5RAP2 is highly expressed in OSCC and its expression correlates with clinical stage and lymph node metastasis of the disease. The expression of CDK5RAP2 is regulated by the Wnt signaling pathway. Depletion of CDK5RAP2 inhibits the tumorigenesis and migration of OSCC cells and alters the OSCC cancer stem (-like) cell (CSC) signature. Notably, suppression of CDK5RAP2 expression disrupts spindle orientation during mitosis. Collectively, these results identify CDK5RAP2 as a potential CSC marker and reveal a mechanism that controls the CSC population in OSCC.
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Affiliation(s)
- Yuehong Shen
- Department of Oral and Maxillofacial Surgery, Stomatological Center, Peking University Shenzhen Hospital; Guangdong Provincial High-level Clinical Key Specialty; Guangdong Province Engineering Research Center of Oral Disease Diagnosis and Treatment; The Institute of Stomatology, Peking University Shenzhen Hospital, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Guangdong, China
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Yuling Chen
- Department of Oral and Maxillofacial Surgery, Stomatological Center, Peking University Shenzhen Hospital; Guangdong Provincial High-level Clinical Key Specialty; Guangdong Province Engineering Research Center of Oral Disease Diagnosis and Treatment; The Institute of Stomatology, Peking University Shenzhen Hospital, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Guangdong, China
| | - Yuntao Lin
- Department of Oral and Maxillofacial Surgery, Stomatological Center, Peking University Shenzhen Hospital; Guangdong Provincial High-level Clinical Key Specialty; Guangdong Province Engineering Research Center of Oral Disease Diagnosis and Treatment; The Institute of Stomatology, Peking University Shenzhen Hospital, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Guangdong, China
| | - Yicun Li
- Department of Oral and Maxillofacial Surgery, Stomatological Center, Peking University Shenzhen Hospital; Guangdong Provincial High-level Clinical Key Specialty; Guangdong Province Engineering Research Center of Oral Disease Diagnosis and Treatment; The Institute of Stomatology, Peking University Shenzhen Hospital, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Guangdong, China
| | - Pengfei Liu
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Biru Zhang
- Department of Oral and Maxillofacial Surgery, Stomatological Center, Peking University Shenzhen Hospital; Guangdong Provincial High-level Clinical Key Specialty; Guangdong Province Engineering Research Center of Oral Disease Diagnosis and Treatment; The Institute of Stomatology, Peking University Shenzhen Hospital, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Guangdong, China
- Department of Stomatology, Shenzhen Luohu People's Hospital, Guangdong, China
| | - Yufan Wang
- Department of Oral and Maxillofacial Surgery, Stomatological Center, Peking University Shenzhen Hospital; Guangdong Provincial High-level Clinical Key Specialty; Guangdong Province Engineering Research Center of Oral Disease Diagnosis and Treatment; The Institute of Stomatology, Peking University Shenzhen Hospital, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Guangdong, China
| | - King-Chi Chan
- Centre for PanorOmic Sciences, The University of Hong Kong, Hong Kong, China
| | - Nai-Ki Mak
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Michael Kahn
- Department of Molecular Medicine, City of Hope, Beckman Research Institute, Duarte, CA, USA
| | - 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, Systems Hub, The Hong Kong University of Science and Technology (Guangzhou), Guangdong, China.
| | - Hongyu Yang
- Department of Oral and Maxillofacial Surgery, Stomatological Center, Peking University Shenzhen Hospital; Guangdong Provincial High-level Clinical Key Specialty; Guangdong Province Engineering Research Center of Oral Disease Diagnosis and Treatment; The Institute of Stomatology, Peking University Shenzhen Hospital, Shenzhen Peking University-The Hong Kong University of Science and Technology Medical Center, Guangdong, China.
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22
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Sreeja JS, Jyothy A, Nellikka RK, Ghorai S, Riya PA, James J, Sengupta S. The centrosomal recruitment of γ-tubulin and its microtubule nucleation activity is α-fodrin guided. Cell Cycle 2023; 22:361-378. [PMID: 36082994 PMCID: PMC9851242 DOI: 10.1080/15384101.2022.2119516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 08/15/2022] [Accepted: 08/22/2022] [Indexed: 01/22/2023] Open
Abstract
The regulation and recruitment of γ-TuRCs, the prime nucleator of microtubules, to the centrosome are still thrust areas of research. The interaction of fodrin, a sub-plasmalemmal cytoskeletal protein, with γ-tubulin is a new area of interest. To understand the cellular significance of this interaction, we show that depletion of α-fodrin brings in a significant reduction of γ-tubulin in neural cell centrosomes making it functionally under-efficient. This causes a loss of nucleation ability that cannot efficiently form microtubules in interphase cells and astral microtubules in mitosis. Fluorescence Recovery after Photobleaching (FRAP) experiment implies that α-fodrin is important in the recruitment of γ-tubulin to the centrosome resulting in the aforementioned effects. Further, our experiments indicate that the interaction of α-fodrin with certain pericentriolar matrix proteins such as Pericentrin and CDK5RAP2 are crucial for the recruitment of γ-tubulin to the centrosome. Earlier we reported that α-fodrin limits the nucleation potential of γ-TuRC. In that context, this study suggests that α-fodrin is a γ-tubulin recruiting protein to the centrosome thus preventing cytoplasmic microtubule nucleation and thereby compartmentalizing the process to the centrosome for maximum efficiency. Summary statementα-fodrin is a γ-tubulin interacting protein that controls the process of γ-tubulin recruitment to the centrosome and thereby regulates the microtubule nucleation capacity spatially and temporally.
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Affiliation(s)
- Jamuna S. Sreeja
- Cancer Research, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, India
| | - Athira Jyothy
- Cancer Research, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, India
- Department of Biotechnology, University of Kerala, Thiruvananthapuram, India
| | - Rohith Kumar Nellikka
- Cancer Research, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, India
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Sayan Ghorai
- Cancer Research, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, India
| | - Paul Ann Riya
- Regenerative Biology, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, India
| | - Jackson James
- Regenerative Biology, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, India
| | - Suparna Sengupta
- Cancer Research, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, India
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23
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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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24
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Berman AY, Wieczorek M, Aher A, Olinares PDB, Chait BT, Kapoor TM. A nucleotide binding-independent role for γ-tubulin in microtubule capping and cell division. J Cell Biol 2023; 222:213828. [PMID: 36695784 PMCID: PMC9930161 DOI: 10.1083/jcb.202204102] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 10/20/2022] [Accepted: 12/22/2022] [Indexed: 01/26/2023] Open
Abstract
The γ-tubulin ring complex (γ-TuRC) has essential roles in centrosomal and non-centrosomal microtubule organization during vertebrate mitosis. While there have been important advances in understanding γ-TuRC-dependent microtubule nucleation, γ-TuRC capping of microtubule minus-ends remains poorly characterized. Here, we utilized biochemical reconstitutions and cellular assays to characterize the human γ-TuRC's capping activity. Single filament assays showed that the γ-TuRC remained associated with a nucleated microtubule for tens of minutes. In contrast, caps at dynamic microtubule minus-ends displayed lifetimes of ∼1 min. Reconstituted γ-TuRCs with nucleotide-binding deficient γ-tubulin (γ-tubulinΔGTP) formed ring-shaped complexes that did not nucleate microtubules but capped microtubule minus-ends with lifetimes similar to those measured for wild-type complexes. In dividing cells, microtubule regrowth assays revealed that while knockdown of γ-tubulin suppressed non-centrosomal microtubule formation, add-back of γ-tubulinΔGTP could substantially restore this process. Our results suggest that γ-TuRC capping is a nucleotide-binding-independent activity that plays a role in non-centrosomal microtubule organization during cell division.
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Affiliation(s)
- Adi Y. Berman
- https://ror.org/0420db125Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY, USA,Tri-Institutional PhD Program in Chemical Biology, The Rockefeller University, New York, NY, USA
| | - Michal Wieczorek
- https://ror.org/0420db125Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY, USA
| | - Amol Aher
- https://ror.org/0420db125Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY, USA
| | - Paul Dominic B. Olinares
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, NY, USA
| | - Brian T. Chait
- Tri-Institutional PhD Program in Chemical Biology, The Rockefeller University, New York, NY, USA,Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, NY, USA
| | - Tarun M. Kapoor
- https://ror.org/0420db125Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY, USA,Tri-Institutional PhD Program in Chemical Biology, The Rockefeller University, New York, NY, USA
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25
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Au FKC, Le KTD, Qi RZ. Detection and Analysis of Microtubule Nucleator γ-Tubulin Ring Complex. Methods Mol Biol 2023; 2557:543-558. [PMID: 36512236 DOI: 10.1007/978-1-0716-2639-9_32] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Golgi-derived microtubules constitute an asymmetrical microtubule network that drives polarized transport of vesicles to support cell polarization and directional migration. Golgi-based microtubule nucleation requires the γ-tubulin ring complex (γTuRC), the principal microtubule nucleator in animal cells. In this chapter, we present methods for detecting γTuRC components and associated proteins on the Golgi, examining Golgi-based microtubule nucleation, and measuring the microtubule-nucleating activity of isolated γTuRCs. These approaches have been demonstrated to be effective for assessing the microtubule-organizing function of the Golgi complex.
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Affiliation(s)
- Franco K C Au
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Kowloon, Hong Kong, China
| | - Khoi T D Le
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Kowloon, 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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26
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Rale MJ, Romer B, Mahon BP, Travis SM, Petry S. The conserved centrosomin motif, γTuNA, forms a dimer that directly activates microtubule nucleation by the γ-tubulin ring complex (γTuRC). eLife 2022; 11:e80053. [PMID: 36515268 PMCID: PMC9859039 DOI: 10.7554/elife.80053] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 12/07/2022] [Indexed: 12/15/2022] Open
Abstract
To establish the microtubule cytoskeleton, the cell must tightly regulate when and where microtubules are nucleated. This regulation involves controlling the initial nucleation template, the γ-tubulin ring complex (γTuRC). Although γTuRC is present throughout the cytoplasm, its activity is restricted to specific sites including the centrosome and Golgi. The well-conserved γ-tubulin nucleation activator (γTuNA) domain has been reported to increase the number of microtubules (MTs) generated by γTuRCs. However, previously we and others observed that γTuNA had a minimal effect on the activity of antibody-purified Xenopus γTuRCs in vitro (Thawani et al., eLife, 2020; Liu et al., 2020). Here, we instead report, based on improved versions of γTuRC, γTuNA, and our TIRF assay, the first real-time observation that γTuNA directly increases γTuRC activity in vitro, which is thus a bona fide γTuRC activator. We further validate this effect in Xenopus egg extract. Via mutation analysis, we find that γTuNA is an obligate dimer. Moreover, efficient dimerization as well as γTuNA's L70, F75, and L77 residues are required for binding to and activation of γTuRC. Finally, we find that γTuNA's activating effect opposes inhibitory regulation by stathmin. In sum, our improved assays prove that direct γTuNA binding strongly activates γTuRCs, explaining previously observed effects of γTuNA expression in cells and illuminating how γTuRC-mediated microtubule nucleation is regulated.
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Affiliation(s)
- Michael J Rale
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
| | - Brianna Romer
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
| | - Brian P Mahon
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
| | - Sophie M Travis
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
| | - Sabine Petry
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
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27
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Nakamura A, Ikeda M, Kusayanagi S, Hayashi K. An alternative splice isoform of mouse CDK5RAP2 induced cytoplasmic microtubule nucleation. IBRO Neurosci Rep 2022; 13:264-273. [PMID: 36164503 PMCID: PMC9508486 DOI: 10.1016/j.ibneur.2022.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 09/11/2022] [Indexed: 10/29/2022] Open
Abstract
The centrosome lacks microtubule (MT)-nucleation activity in differentiated neurons. We have previously demonstrated that MTs were nucleated at the cytoplasm of mouse neurons. They are supposed to serve seeds for MTs required for dendrite growth. However, the factors that activate the cytoplasmic γ-tubulin ring complex (γTuRC) are unknown. Here we report an alternative splicing isoform of cyclin-dependent kinase 5 regulatory subunit-associated protein 2 (CKD5RAP2) as a candidate for the cytoplasmic γTuRC activator. This isoform lacked exon 17 and was expressed predominantly in the brain and testis. The expression was transient during the development of cortical neurons, which period coincided with the period we reported cytoplasmic MT nucleation. This isoform resulted in a frameshift and generated truncated protein without a centrosomal localization signal. When this isoform was expressed in cells, it localized diffusely in the cytoplasm. It was co-immunoprecipitated with γ-tubulin and MOZART2, suggesting that it can activate cytosolic γTuRCs. After cold-nocodazole depolymerization of MTs and subsequent washout, we observed numerous short MTs in the cytoplasm of cells transfected with the cDNA of this isoform. The isoform-overexpressing cells exhibited an increased amount of MTs and a decreased ratio of acetylated tubulin, suggesting that MT generation and turnover were enhanced by the isoform. Our data suggest the possibility that alternative splicing of CDK5RAP2 induces cytoplasmic nucleation of MTs in developing neurons.
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Key Words
- CKD5RAP2, cyclin-dependent kinase 5 regulatory subunit-associated protein 2
- CM1, centrosomin motif 1
- Centrosome
- DMEM, Dulbecco’s Modified Eagle’s Medium
- Dendrite growth
- FBS, fetal bovine serum
- HBSS, Hanks' Balanced Salt Solution
- IB, immunoblotting
- IP, immunoprecipitation
- MT, microtubule
- MZT2
- MZT2, MOZART2
- Microcephaly
- NSD, nonsense-mediated mRNA decay
- Neuron differentiation
- PBS, phosphate-buffered saline
- PCR, polymerase chain reaction
- γTuRC
- γTuRC, γ-tubulin ring complex
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Affiliation(s)
- Akari Nakamura
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Tokyo, Japan
| | - Mami Ikeda
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Tokyo, Japan
| | - Seina Kusayanagi
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Tokyo, Japan
| | - Kensuke Hayashi
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Tokyo, Japan
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28
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Abstract
The centrosome, consisting of centrioles and the associated pericentriolar material, is the main microtubule-organizing centre (MTOC) in animal cells. During most of interphase, the two centrosomes of a cell are joined together by centrosome cohesion into one MTOC. The most dominant element of centrosome cohesion is the centrosome linker, an interdigitating, fibrous network formed by the protein C-Nap1 anchoring a number of coiled-coil proteins including rootletin to the proximal end of centrioles. Alternatively, centrosomes can be kept together by the action of the minus end directed kinesin motor protein KIFC3 that works on interdigitating microtubules organized by both centrosomes and probably by the actin network. Although cells connect the two interphase centrosomes by several mechanisms into one MTOC, the general importance of centrosome cohesion, particularly for an organism, is still largely unclear. In this article, we review the functions of the centrosome linker and discuss how centrosome cohesion defects can lead to diseases.
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Affiliation(s)
- Hairuo Dang
- Zentrum für Molekulare Biologie der Universität Heidelberg, Deutsches Krebsforschungszentrum-ZMBH Allianz, and,Heidelberg Biosciences International Graduate School (HBIGS), Universität Heidelberg, Heidelberg 69120, Germany
| | - Elmar Schiebel
- Zentrum für Molekulare Biologie der Universität Heidelberg, Deutsches Krebsforschungszentrum-ZMBH Allianz, and
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29
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Sulimenko V, Dráberová E, Dráber P. γ-Tubulin in microtubule nucleation and beyond. Front Cell Dev Biol 2022; 10:880761. [PMID: 36158181 PMCID: PMC9503634 DOI: 10.3389/fcell.2022.880761] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 08/03/2022] [Indexed: 11/13/2022] Open
Abstract
Microtubules composed of αβ-tubulin dimers are dynamic cytoskeletal polymers that play key roles in essential cellular processes such as cell division, organelle positioning, intracellular transport, and cell migration. γ-Tubulin is a highly conserved member of the tubulin family that is required for microtubule nucleation. γ-Tubulin, together with its associated proteins, forms the γ-tubulin ring complex (γ-TuRC), that templates microtubules. Here we review recent advances in the structure of γ-TuRC, its activation, and centrosomal recruitment. This provides new mechanistic insights into the molecular mechanism of microtubule nucleation. Accumulating data suggest that γ-tubulin also has other, less well understood functions. We discuss emerging evidence that γ-tubulin can form oligomers and filaments, has specific nuclear functions, and might be involved in centrosomal cross-talk between microtubules and microfilaments.
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Affiliation(s)
| | | | - Pavel Dráber
- *Correspondence: Vadym Sulimenko, ; Pavel Dráber,
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30
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Willekers S, Tessadori F, van der Vaart B, Henning HH, Stucchi R, Altelaar M, Roelen BAJ, Akhmanova A, Bakkers J. The centriolar satellite protein Cfap53 facilitates formation of the zygotic microtubule organizing center in the zebrafish embryo. Development 2022; 149:dev198762. [PMID: 35980365 PMCID: PMC9481976 DOI: 10.1242/dev.198762] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 07/20/2022] [Indexed: 12/02/2023]
Abstract
In embryos of most animal species, the zygotic centrosome is assembled by the centriole derived from the sperm cell and pericentriolar proteins present in the oocyte. This zygotic centrosome acts as a microtubule organizing center (MTOC) to assemble the sperm aster and mitotic spindle. As MTOC formation has been studied mainly in adult cells, very little is known about the formation of the zygotic MTOC. Here, we show that zebrafish (Danio rerio) embryos lacking either maternal or paternal Cfap53, a centriolar satellite protein, arrest during the first cell cycle. Although Cfap53 is dispensable for sperm aster function, it aids proper formation of the mitotic spindle. During cell division, Cfap53 colocalizes with γ-tubulin and with other centrosomal and centriolar satellite proteins at the MTOC. Furthermore, we find that γ-tubulin localization at the MTOC is impaired in the absence of Cfap53. Based on these results, we propose a model in which Cfap53 deposited in the oocyte and the sperm participates in the organization of the zygotic MTOC to allow mitotic spindle formation.
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Affiliation(s)
- Sven Willekers
- Hubrecht Institute-KNAW, Utrecht 3584 CT, The Netherlands
| | | | - Babet van der Vaart
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Heiko H. Henning
- Equine Sciences, Department Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht 3584 CM, The Netherlands
| | - Riccardo Stucchi
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht 3584 CH, The Netherlands
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Maarten Altelaar
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Bernard A. J. Roelen
- Embryology, Anatomy and Physiology, Department Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht 3584 CT, The Netherlands
| | - Anna Akhmanova
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Jeroen Bakkers
- Hubrecht Institute-KNAW, Utrecht 3584 CT, The Netherlands
- Department of Pediatric Cardiology, Division of Pediatrics, University Medical Center Utrecht, Utrecht 3584 EA, The Netherlands
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31
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Batman U, Deretic J, Firat-Karalar EN. The ciliopathy protein CCDC66 controls mitotic progression and cytokinesis by promoting microtubule nucleation and organization. PLoS Biol 2022; 20:e3001708. [PMID: 35849559 PMCID: PMC9333452 DOI: 10.1371/journal.pbio.3001708] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 07/28/2022] [Accepted: 06/14/2022] [Indexed: 11/23/2022] Open
Abstract
Precise spatiotemporal control of microtubule nucleation and organization is critical for faithful segregation of cytoplasmic and genetic material during cell division and signaling via the primary cilium in quiescent cells. Microtubule-associated proteins (MAPs) govern assembly, maintenance, and remodeling of diverse microtubule arrays. While a set of conserved MAPs are only active during cell division, an emerging group of MAPs acts as dual regulators in dividing and nondividing cells. Here, we elucidated the nonciliary functions and molecular mechanism of action of the ciliopathy-linked protein CCDC66, which we previously characterized as a regulator of ciliogenesis in quiescent cells. We showed that CCDC66 dynamically localizes to the centrosomes, the bipolar spindle, the spindle midzone, the central spindle, and the midbody in dividing cells and interacts with the core machinery of centrosome maturation and MAPs involved in cell division. Loss-of-function experiments revealed its functions during mitotic progression and cytokinesis. Specifically, CCDC66 depletion resulted in defective spindle assembly and orientation, kinetochore fiber stability, chromosome alignment in metaphase as well as central spindle and midbody assembly and organization in anaphase and cytokinesis. Notably, CCDC66 regulates mitotic microtubule nucleation via noncentrosomal and centrosomal pathways via recruitment of gamma-tubulin to the centrosomes and the spindle. Additionally, CCDC66 bundles microtubules in vitro and in cells by its C-terminal microtubule-binding domain. Phenotypic rescue experiments showed that the microtubule and centrosome-associated pools of CCDC66 individually or cooperatively mediate its mitotic and cytokinetic functions. Collectively, our findings identify CCDC66 as a multifaceted regulator of the nucleation and organization of the diverse mitotic and cytokinetic microtubule arrays and provide new insight into nonciliary defects that underlie ciliopathies. The ciliopathy-linked protein CCDC66 is only known for its ciliary functions. This study reveals that CCDC66 also has extensive non-ciliary functions, localizing to the spindle poles, spindle midzone, central spindle and midbody throughout cell division, where it regulates mitosis and cytokinesis by promoting microtubule nucleation and organization.
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Affiliation(s)
- Umut Batman
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Jovana Deretic
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Elif Nur Firat-Karalar
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
- Koç University School of Medicine, Istanbul, Turkey
- * E-mail:
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32
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Chen F, Wu J, Iwanski MK, Jurriens D, Sandron A, Pasolli M, Puma G, Kromhout JZ, Yang C, Nijenhuis W, Kapitein LC, Berger F, Akhmanova A. Self-assembly of pericentriolar material in interphase cells lacking centrioles. eLife 2022; 11:77892. [PMID: 35787744 PMCID: PMC9307276 DOI: 10.7554/elife.77892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 07/04/2022] [Indexed: 11/18/2022] Open
Abstract
The major microtubule-organizing center (MTOC) in animal cells, the centrosome, comprises a pair of centrioles surrounded by pericentriolar material (PCM), which nucleates and anchors microtubules. Centrosome assembly depends on PCM binding to centrioles, PCM self-association and dynein-mediated PCM transport, but the self-assembly properties of PCM components in interphase cells are poorly understood. Here, we used experiments and modeling to study centriole-independent features of interphase PCM assembly. We showed that when centrioles are lost due to PLK4 depletion or inhibition, dynein-based transport and self-clustering of PCM proteins are sufficient to form a single compact MTOC, which generates a dense radial microtubule array. Interphase self-assembly of PCM components depends on γ-tubulin, pericentrin, CDK5RAP2 and ninein, but not NEDD1, CEP152, or CEP192. Formation of a compact acentriolar MTOC is inhibited by AKAP450-dependent PCM recruitment to the Golgi or by randomly organized CAMSAP2-stabilized microtubules, which keep PCM mobile and prevent its coalescence. Linking of CAMSAP2 to a minus-end-directed motor leads to the formation of an MTOC, but MTOC compaction requires cooperation with pericentrin-containing self-clustering PCM. Our data reveal that interphase PCM contains a set of components that can self-assemble into a compact structure and organize microtubules, but PCM self-organization is sensitive to motor- and microtubule-based rearrangement.
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Affiliation(s)
- Fangrui Chen
- Department of Biology, Utrecht University, Utrecht, Netherlands
| | - Jingchao Wu
- Department of Biology, Utrecht University, Utrecht, Netherlands
| | | | - Daphne Jurriens
- Department of Biology, Utrecht University, Utrecht, Netherlands
| | - Arianna Sandron
- Department of Biology, Utrecht University, Utrecht, Netherlands
| | - Milena Pasolli
- Department of Biology, Utrecht University, Utrecht, Netherlands
| | - Gianmarco Puma
- Department of Biology, Utrecht University, Utrecht, Netherlands
| | | | - Chao Yang
- Department of Biology, Utrecht University, Utrecht, Netherlands
| | - Wilco Nijenhuis
- Department of Biology, Utrecht University, Utrecht, Netherlands
| | | | - Florian Berger
- Department of Biology, Utrecht University, Utrecht, Netherlands
| | - Anna Akhmanova
- Department of Biology, Utrecht University, Utrecht, Netherlands
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33
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Zhang Y, Hong X, Hua S, Jiang K. Reconstitution and mechanistic dissection of the human microtubule branching machinery. J Cell Biol 2022; 221:e202109053. [PMID: 35604367 PMCID: PMC9129923 DOI: 10.1083/jcb.202109053] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 03/07/2022] [Accepted: 05/02/2022] [Indexed: 01/07/2023] Open
Abstract
Branching microtubule (MT) nucleation is mediated by the augmin complex and γ-tubulin ring complex (γ-TuRC). However, how these two complexes work together to promote this process remains elusive. Here, using purified components from native and recombinant sources, we demonstrate that human augmin and γ-TuRC are sufficient to reconstitute the minimal MT branching machinery, in which NEDD1 bridges between augmin holo complex and GCP3/MZT1 subcomplex of γ-TuRC. The single-molecule experiment suggests that oligomerization of augmin may activate the branching machinery. We provide direct biochemical evidence that CDK1- and PLK1-dependent phosphorylation are crucial for NEDD1 binding to augmin, for their synergistic MT-binding activities, and hence for branching MT nucleation. In addition, we unveil that NEDD1 possesses an unanticipated intrinsic affinity for MTs via its WD40 domain, which also plays a pivotal role in the branching process. In summary, our study provides a comprehensive understanding of the underlying mechanisms of branching MT nucleation in human cells.
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Affiliation(s)
- Yaqian Zhang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology and Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, China
- Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Wuhan University, Wuhan, China
| | - Xing Hong
- The State Key Laboratory Breeding Base of Basic Science of Stomatology and Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, China
- Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Wuhan University, Wuhan, China
| | - Shasha Hua
- The State Key Laboratory Breeding Base of Basic Science of Stomatology and Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, China
- Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Wuhan University, Wuhan, China
| | - Kai Jiang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology and Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Wuhan University, Wuhan, China
- Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Wuhan University, Wuhan, China
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34
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Merenich D, Nakos K, Pompan T, Donovan SJ, Gill A, Patel P, Spiliotis ET, Myers KA. Septins guide noncentrosomal microtubules to promote focal adhesion disassembly in migrating cells. Mol Biol Cell 2022; 33:ar40. [PMID: 35274967 PMCID: PMC9282018 DOI: 10.1091/mbc.e21-06-0334] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 02/07/2022] [Accepted: 03/04/2022] [Indexed: 11/30/2022] Open
Abstract
Endothelial cell migration is critical for vascular angiogenesis and is compromised to facilitate tumor metastasis. The migratory process requires the coordinated assembly and disassembly of focal adhesions (FA), actin, and microtubules (MT). MT dynamics at FAs deliver vesicular cargoes and enhance actomyosin contractility to promote FA turnover and facilitate cell advance. Noncentrosomal (NC) MTs regulate FA dynamics and are sufficient to drive cell polarity, but how NC MTs target FAs to control FA turnover is not understood. Here, we show that Rac1 induces the assembly of FA-proximal septin filaments that promote NC MT growth into FAs and inhibit mitotic centromere-associated kinesin (MCAK)-associated MT disassembly, thereby maintaining intact MT plus ends proximal to FAs. Septin-associated MT rescue is coupled with accumulation of Aurora-A kinase and cytoplasmic linker-associated protein (CLASP) localization to the MT between septin and FAs. In this way, NC MTs are strategically positioned to undergo MCAK- and CLASP-regulated bouts of assembly and disassembly into FAs, thereby regulating FA turnover and cell migration.
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Affiliation(s)
- Daniel Merenich
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA 19104
| | | | - Taylor Pompan
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA 19104
| | - Samantha J. Donovan
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA 19104
| | - Amrik Gill
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA 19104
| | - Pranav Patel
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA 19104
| | | | - Kenneth A. Myers
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA 19104
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35
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Real-Time Imaging of Single γTuRC-Mediated Microtubule Nucleation Events In Vitro by TIRF Microscopy. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2022; 2430:315-336. [PMID: 35476342 DOI: 10.1007/978-1-0716-1983-4_21] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The γ-tubulin ring complex (γTuRC) is the major microtubule nucleator in cells. How γTuRC nucleates microtubules, and how nucleation is regulated is not understood. To gain an understanding of γTuRC activity and regulation at the molecular level, it is important to measure quantitatively how γTuRC interacts with tubulin and potential regulators in space and time. Here, we describe a total internal reflection fluorescence microscopy-based assay on chemically functionalized glass slides for the in vitro study of surface immobilized purified γTuRC. The assay allows to measure microtubule nucleation by γTuRC in real time and at a single molecule level over a wide variety of assay conditions, in the absence and presence of potential regulators. This setup provides a previously unavailable opportunity for quantitative studies of the kinetics of microtubule nucleation by γTuRC.
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36
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Ching K, Wang JT, Stearns T. Long-range migration of centrioles to the apical surface of the olfactory epithelium. eLife 2022; 11:e74399. [PMID: 35420544 PMCID: PMC9064291 DOI: 10.7554/elife.74399] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Accepted: 04/13/2022] [Indexed: 02/07/2023] Open
Abstract
Olfactory sensory neurons (OSNs) in vertebrates detect odorants using multiple cilia, which protrude from the end of the dendrite and require centrioles for their formation. In mouse olfactory epithelium, the centrioles originate in progenitor cells near the basal lamina, often 50-100 μm from the apical surface. It is unknown how centrioles traverse this distance or mature to form cilia. Using high-resolution expansion microscopy, we found that centrioles migrate together, with multiple centrioles per group and multiple groups per OSN, during dendrite outgrowth. Centrioles were found by live imaging to migrate slowly, with a maximum rate of 0.18 µm/minute. Centrioles in migrating groups were associated with microtubule nucleation factors, but acquired rootletin and appendages only in mature OSNs. The parental centriole had preexisting appendages, formed a single cilium before other centrioles, and retained its unique appendage configuration in the mature OSN. We developed an air-liquid interface explant culture system for OSNs and used it to show that centriole migration can be perturbed ex vivo by stabilizing microtubules. We consider these results in the context of a comprehensive model for centriole formation, migration, and maturation in this important sensory cell type.
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Affiliation(s)
- Kaitlin Ching
- Department of Biology, Stanford UniversityStanfordUnited States
| | - Jennifer T Wang
- Department of Biology, Stanford UniversityStanfordUnited States
| | - Tim Stearns
- Department of Biology, Stanford UniversityStanfordUnited States
- Department of Genetics, Stanford University School of MedicineStanfordUnited States
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37
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Pomp O, Lim HYG, Skory RM, Moverley AA, Tetlak P, Bissiere S, Plachta N. A monoastral mitotic spindle determines lineage fate and position in the mouse embryo. Nat Cell Biol 2022; 24:155-167. [PMID: 35102267 DOI: 10.1038/s41556-021-00826-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 11/30/2021] [Indexed: 12/11/2022]
Abstract
During mammalian development, the first asymmetric cell divisions segregate cells into inner and outer positions of the embryo to establish the pluripotent and trophectoderm lineages. Typically, polarity components differentially regulate the mitotic spindle via astral microtubule arrays to trigger asymmetric division patterns. However, early mouse embryos lack centrosomes, the microtubule-organizing centres (MTOCs) that usually generate microtubule asters. Thus, it remains unknown whether spindle organization regulates lineage segregation. Here we find that heterogeneities in cell polarity in the early 8-cell-stage mouse embryo trigger the assembly of a highly asymmetric spindle organization. This spindle arises in an unusual modular manner, forming a single microtubule aster from an apically localized, non-centrosomal MTOC, before joining it to the rest of the spindle apparatus. When fully assembled, this 'monoastral' spindle triggers spatially asymmetric division patterns to segregate cells into inner and outer positions. Moreover, the asymmetric inheritance of spindle components causes differential cell polarization to determine pluripotent versus trophectoderm lineage fate.
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Affiliation(s)
- Oz Pomp
- Department of Cell and Developmental Biology, Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Hui Yi Grace Lim
- Institute of Molecular and Cell Biology, ASTAR, Singapore, Singapore
| | - Robin M Skory
- Department of Cell and Developmental Biology, Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Adam A Moverley
- Department of Cell and Developmental Biology, Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Piotr Tetlak
- Department of Cell and Developmental Biology, Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Stephanie Bissiere
- Department of Cell and Developmental Biology, Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Nicolas Plachta
- Department of Cell and Developmental Biology, Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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38
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Würtz M, Zupa E, Atorino ES, Neuner A, Böhler A, Rahadian AS, Vermeulen BJA, Tonon G, Eustermann S, Schiebel E, Pfeffer S. Modular assembly of the principal microtubule nucleator γ-TuRC. Nat Commun 2022; 13:473. [PMID: 35078983 PMCID: PMC8789826 DOI: 10.1038/s41467-022-28079-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Accepted: 01/07/2022] [Indexed: 12/15/2022] Open
Abstract
AbstractThe gamma-tubulin ring complex (γ-TuRC) is the principal microtubule nucleation template in vertebrates. Recent cryo-EM reconstructions visualized the intricate quaternary structure of the γ-TuRC, containing more than thirty subunits, raising fundamental questions about γ-TuRC assembly and the role of actin as an integral part of the complex. Here, we reveal the structural mechanism underlying modular γ-TuRC assembly and identify a functional role of actin in microtubule nucleation. During γ-TuRC assembly, a GCP6-stabilized core comprising GCP2-3-4-5-4-6 is expanded by stepwise recruitment, selective stabilization and conformational locking of four pre-formed GCP2-GCP3 units. Formation of the lumenal bridge specifies incorporation of the terminal GCP2-GCP3 unit and thereby leads to closure of the γ-TuRC ring in a left-handed spiral configuration. Actin incorporation into the complex is not relevant for γ-TuRC assembly and structural integrity, but determines γ-TuRC geometry and is required for efficient microtubule nucleation and mitotic chromosome alignment in vivo.
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39
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Tsuchiya K, Goshima G. Microtubule-associated proteins promote microtubule generation in the absence of γ-tubulin in human colon cancer cells. J Cell Biol 2021; 220:e202104114. [PMID: 34779859 PMCID: PMC8598081 DOI: 10.1083/jcb.202104114] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 08/13/2021] [Accepted: 09/20/2021] [Indexed: 11/29/2022] Open
Abstract
The γ-tubulin complex acts as the predominant microtubule (MT) nucleator that initiates MT formation and is therefore an essential factor for cell proliferation. Nonetheless, cellular MTs are formed after experimental depletion of the γ-tubulin complex, suggesting that cells possess other factors that drive MT nucleation. Here, by combining gene knockout, auxin-inducible degron, RNA interference, MT depolymerization/regrowth assay, and live microscopy, we identified four microtubule-associated proteins (MAPs), ch-TOG, CLASP1, CAMSAPs, and TPX2, which are involved in γ-tubulin-independent MT generation in human colon cancer cells. In the mitotic MT regrowth assay, nucleated MTs organized noncentriolar MT organizing centers (ncMTOCs) in the absence of γ-tubulin. Depletion of CLASP1 or TPX2 substantially delayed ncMTOC formation, suggesting that these proteins might promote MT nucleation in the absence of γ-tubulin. In contrast, depletion of ch-TOG or CAMSAPs did not affect the timing of ncMTOC appearance. CLASP1 also accelerates γ-tubulin-independent MT regrowth during interphase. Thus, MT generation can be promoted by MAPs without the γ-tubulin template.
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Affiliation(s)
- Kenta Tsuchiya
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Gohta Goshima
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
- Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Nagoya, Japan
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40
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Dráber P, Dráberová E. Dysregulation of Microtubule Nucleating Proteins in Cancer Cells. Cancers (Basel) 2021; 13:cancers13225638. [PMID: 34830792 PMCID: PMC8616210 DOI: 10.3390/cancers13225638] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 11/06/2021] [Accepted: 11/08/2021] [Indexed: 12/12/2022] Open
Abstract
Simple Summary The dysfunction of microtubule nucleation in cancer cells changes the overall cytoskeleton organization and cellular physiology. This review focuses on the dysregulation of the γ-tubulin ring complex (γ-TuRC) proteins that are essential for microtubule nucleation. Recent research on the high-resolution structure of γ-TuRC has brought new insight into the microtubule nucleation mechanism. We discuss the effect of γ-TuRC protein overexpression on cancer cell behavior and new drugs directed to γ-tubulin that may offer a viable alternative to microtubule-targeting agents currently used in cancer chemotherapy. Abstract In cells, microtubules typically nucleate from microtubule organizing centers, such as centrosomes. γ-Tubulin, which forms multiprotein complexes, is essential for nucleation. The γ-tubulin ring complex (γ-TuRC) is an efficient microtubule nucleator that requires additional centrosomal proteins for its activation and targeting. Evidence suggests that there is a dysfunction of centrosomal microtubule nucleation in cancer cells. Despite decades of molecular analysis of γ-TuRC and its interacting factors, the mechanisms of microtubule nucleation in normal and cancer cells remains obscure. Here, we review recent work on the high-resolution structure of γ-TuRC, which brings new insight into the mechanism of microtubule nucleation. We discuss the effects of γ-TuRC protein dysregulation on cancer cell behavior and new compounds targeting γ-tubulin. Drugs inhibiting γ-TuRC functions could represent an alternative to microtubule targeting agents in cancer chemotherapy.
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41
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Wieczorek M, Ti SC, Urnavicius L, Molloy KR, Aher A, Chait BT, Kapoor TM. Biochemical reconstitutions reveal principles of human γ-TuRC assembly and function. J Cell Biol 2021; 220:211719. [PMID: 33496729 PMCID: PMC7844428 DOI: 10.1083/jcb.202009146] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 12/10/2020] [Accepted: 01/04/2021] [Indexed: 12/22/2022] Open
Abstract
The formation of cellular microtubule networks is regulated by the γ-tubulin ring complex (γ-TuRC). This ∼2.3 MD assembly of >31 proteins includes γ-tubulin and GCP2-6, as well as MZT1 and an actin-like protein in a “lumenal bridge” (LB). The challenge of reconstituting the γ-TuRC has limited dissections of its assembly and function. Here, we report a biochemical reconstitution of the human γ-TuRC (γ-TuRC-GFP) as a ∼35 S complex that nucleates microtubules in vitro. In addition, we generate a subcomplex, γ-TuRCΔLB-GFP, which lacks MZT1 and actin. We show that γ-TuRCΔLB-GFP nucleates microtubules in a guanine nucleotide–dependent manner and with similar efficiency as the holocomplex. Electron microscopy reveals that γ-TuRC-GFP resembles the native γ-TuRC architecture, while γ-TuRCΔLB-GFP adopts a partial cone shape presenting only 8–10 γ-tubulin subunits and lacks a well-ordered lumenal bridge. Our results show that the γ-TuRC can be reconstituted using a limited set of proteins and suggest that the LB facilitates the self-assembly of regulatory interfaces around a microtubule-nucleating “core” in the holocomplex.
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Affiliation(s)
- Michal Wieczorek
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY
| | - Shih-Chieh Ti
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY
| | - Linas Urnavicius
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY.,Laboratory of Cell Biology, The Rockefeller University, New York, NY
| | - Kelly R Molloy
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, NY
| | - Amol Aher
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY
| | - Brian T Chait
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, NY
| | - Tarun M Kapoor
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY
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42
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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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43
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Abstract
Centrioles are microtubule-based cylindrical structures that assemble the centrosome and template the formation of cilia. The proximal part of centrioles is associated with the pericentriolar material, a protein scaffold from which microtubules are nucleated. This activity is mediated by the γ-tubulin ring complex (γTuRC) whose central role in centrosomal microtubule organization has been recognized for decades. However, accumulating evidence suggests that γTuRC activity at this organelle is neither restricted to the pericentriolar material nor limited to microtubule nucleation. Instead, γTuRC is found along the entire centriole cylinder, at subdistal appendages, and inside the centriole lumen, where its canonical function as a microtubule nucleator might be supplemented or replaced by a function in microtubule anchoring and centriole stabilization, respectively. In this Opinion, we discuss recent insights into the expanded repertoire of γTuRC activities at centrioles and how distinct subpopulations of γTuRC might act in concert to ensure centrosome and cilia biogenesis and function, ultimately supporting cell proliferation, differentiation and homeostasis. We propose that the classical view of centrosomal γTuRC as a pericentriolar material-associated microtubule nucleator needs to be revised.
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Affiliation(s)
- Nina Schweizer
- Mechanisms of Disease Programme, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028 Barcelona, Spain
| | - Jens Lüders
- Mechanisms of Disease Programme, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028 Barcelona, Spain
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44
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Yin C, Lui ESW, Jiang T, Qi RZ. Proteolysis of γ-tubulin small complex proteins is mediated by the ubiquitin-proteasome system. FEBS Lett 2021; 595:1987-1996. [PMID: 34107052 DOI: 10.1002/1873-3468.14146] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 05/23/2021] [Accepted: 06/02/2021] [Indexed: 11/12/2022]
Abstract
Microtubule nucleation is mainly mediated by the γ-tubulin ring complex (γTuRC), whose core components are γ-tubulin and γ-tubulin complex proteins GCP2-6. A substantial fraction of γ-tubulin also exists with GCP2 and GCP3 in a tetramer called the γ-tubulin small complex (γTuSC). To date, the mechanisms underlying the turnover of γ-tubulin and GCPs have remained unclear. Here, we show that γ-tubulin, GCP2, and GCP3 are proteolyzed by the ubiquitin-proteasome system, and we identify cullin 1, cullin 4A, and cullin 4B as the E3 ligases that mediate the ubiquitination and, consequently, the degradation of γ-tubulin. Notably, we found that γTuSC disassembly promotes the degradation of γ-tubulin, GCP2, and GCP3, which indicates a role for γTuSCs in the stabilization of its components.
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Affiliation(s)
- Can Yin
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, China
| | - Edna S W Lui
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, China
| | - Taolue Jiang
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, China
| | - Robert Z Qi
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, China
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45
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Böhler A, Vermeulen BJA, Würtz M, Zupa E, Pfeffer S, Schiebel E. The gamma-tubulin ring complex: Deciphering the molecular organization and assembly mechanism of a major vertebrate microtubule nucleator. Bioessays 2021; 43:e2100114. [PMID: 34160844 DOI: 10.1002/bies.202100114] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 06/07/2021] [Accepted: 06/09/2021] [Indexed: 11/10/2022]
Abstract
Microtubules are protein cylinders with functions in cell motility, signal sensing, cell organization, intracellular transport, and chromosome segregation. One of the key properties of microtubules is their dynamic architecture, allowing them to grow and shrink in length by adding or removing copies of their basic subunit, the heterodimer αβ-tubulin. In higher eukaryotes, de novo assembly of microtubules from αβ-tubulin is initiated by a 2 MDa multi-subunit complex, the gamma-tubulin ring complex (γ-TuRC). For many years, the structure of the γ-TuRC and the function of its subunits remained enigmatic, although structural data from the much simpler yeast counterpart, the γ-tubulin small complex (γ-TuSC), were available. Two recent breakthroughs in the field, high-resolution structural analysis and recombinant reconstitution of the complex, have revolutionized our knowledge about the architecture and function of the γ-TuRC and will form the basis for addressing outstanding questions about biogenesis and regulation of this essential microtubule organizer.
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Affiliation(s)
- Anna Böhler
- Zentrum für Molekulare Biologie der Universität Heidelberg, Heidelberg, Germany
| | - Bram J A Vermeulen
- Zentrum für Molekulare Biologie der Universität Heidelberg, Heidelberg, Germany
| | - Martin Würtz
- Zentrum für Molekulare Biologie der Universität Heidelberg, Heidelberg, Germany
| | - Erik Zupa
- Zentrum für Molekulare Biologie der Universität Heidelberg, Heidelberg, Germany
| | - Stefan Pfeffer
- Zentrum für Molekulare Biologie der Universität Heidelberg, Heidelberg, Germany
| | - Elmar Schiebel
- Zentrum für Molekulare Biologie der Universität Heidelberg, Heidelberg, Germany
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46
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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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Wang X, Baumann C, De La Fuente R, Viveiros MM. CEP215 and AURKA regulate spindle pole focusing and aMTOC organization in mouse oocytes. Reproduction 2021; 159:261-274. [PMID: 31895686 DOI: 10.1530/rep-19-0263] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 01/02/2020] [Indexed: 01/28/2023]
Abstract
Acentriolar microtubule-organizing centers (aMTOCs) play a critical role in stable meiotic spindle assembly in oocytes, necessary for accurate chromosome segregation. Yet, there is a limited understanding of the essential regulatory components of these unique MTOCs. In somatic cells, CEP215 (Centrosomal Protein 215) serves as an important regulator of centrosome maturation and spindle organization. Here, we assessed whether it has a similar function in mouse oocytes. CEP215 was detected in oocyte lysates and specifically localized to aMTOCs throughout the progression of meiosis in a pericentrin-dependent manner. Super-resolution microscopy revealed CEP215 co-localization with pericentrin and a unique pore/ring-like structural organization of aMTOCs. Interestingly, inhibition of Aurora Kinase A in either MI or MII-stage oocytes resulted in a striking loss of the ring-like aMTOC organization and pronounced CEP215 clustering at spindle poles, as well as shorter spindles with highly focused poles. In vitro siRNA-mediated transcript knockdown effectively reduced CEP215 in approximately 85% of the oocytes. Maturation rates to MII were similar in the Cep215 siRNA and injected controls; however, a high percentage (~40%) of the Cep215-knockdown oocytes showed notable variations in spindle pole focusing. Surprisingly, pericentrin and γ-tubulin localization and fluorescence intensity at aMTOCs were unaltered in knockdown oocytes, contrasting with mitotic cells where CEP215 depletion reduced γ-tubulin at centrosomes. Our results demonstrate that CEP215 is a functional component of oocyte aMTOCs and participates in the regulation of meiotic spindle pole focusing. Moreover, these studies reveal a vital role for Aurora Kinase A activity in the maintenance of aMTOC organization in oocytes.
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Affiliation(s)
- Xiaotian Wang
- Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
| | - Claudia Baumann
- Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
| | - Rabindranath De La Fuente
- Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
| | - Maria M Viveiros
- Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
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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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Wieczorek M, Huang TL, Urnavicius L, Hsia KC, Kapoor TM. MZT Proteins Form Multi-Faceted Structural Modules in the γ-Tubulin Ring Complex. Cell Rep 2021; 31:107791. [PMID: 32610146 PMCID: PMC7416306 DOI: 10.1016/j.celrep.2020.107791] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 03/16/2020] [Accepted: 05/29/2020] [Indexed: 02/06/2023] Open
Abstract
Microtubule organization depends on the γ-Tubulin ring complex (γ-TuRC), a ~2.3-MDa nucleation factor comprising an asymmetric assembly of γ-Tubulin and GCP2-GCP6. However, it is currently unclear how the γ-TuRC-associated microproteins MZT1 and MZT2 contribute to the structure and regulation of the holocomplex. Here, we report cryo-EM structures of MZT1 and MZT2 in the context of the native human γ-TuRC. MZT1 forms two subcomplexes with the N-terminal α-helical domains of GCP3 or GCP6 (GCP-NHDs) within the γ-TuRC “lumenal bridge.” We determine the X-ray structure of recombinant MZT1/GCP6-NHD and find it is similar to that within the native γ-TuRC. We identify two additional MZT/GCP-NHD-like subcomplexes, one of which is located on the outer face of the γ-TuRC and comprises MZT2 and GCP2-NHD in complex with a centrosomin motif 1 (CM1)-containing peptide. Our data reveal how MZT1 and MZT2 establish multi-faceted, structurally mimetic “modules” that can expand structural and regulatory interfaces in the γ-TuRC. Wieczorek et al. show how the microproteins MZT1 and MZT2 expand binding interfaces across the γ-TuRC—the cell’s microtubule nucleating machinery—by forming similarly shaped, “modular” subcomplexes with the α-helical N-terminal domains of different γ-Tubulin complex proteins (GCPs).
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Affiliation(s)
- Michal Wieczorek
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Tzu-Lun Huang
- Molecular and Cell Biology, Taiwan International Graduate Program, Academia Sinica, and National Defense Medical Center, Taipei, Taiwan; Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Linas Urnavicius
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA; Laboratory of Cell Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Kuo-Chiang Hsia
- Molecular and Cell Biology, Taiwan International Graduate Program, Academia Sinica, and National Defense Medical Center, Taipei, Taiwan; Institute of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan; Institute of Biochemistry and Molecular Biology, College of Life Sciences, National Yang-Ming University, Taipei 11221, Taiwan.
| | - Tarun M Kapoor
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
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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: 30] [Impact Index Per Article: 10.0] [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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