1
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Zhou Y, Yang J, Huang L, Liu C, Yu M, Chen R, Zhou Q. Nudt21-mediated alternative polyadenylation of MZT1 3'UTR contributes to pancreatic cancer progression. iScience 2024; 27:108822. [PMID: 38303721 PMCID: PMC10831950 DOI: 10.1016/j.isci.2024.108822] [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: 07/18/2023] [Revised: 11/26/2023] [Accepted: 01/02/2024] [Indexed: 02/03/2024] Open
Abstract
Alternative polyadenylation (APA) is an important post-transcriptional regulatory mechanism and is involved in many diseases, but its function and mechanism in regulating pancreatic cancer (PC) pathogenesis remain unclear. In this study, we found that the 3' UTR shortening of MZT1 was the most prominent APA event in PC liver metastases. The short-3'UTR isoform exerted a stronger effect in promoting cell proliferation and migration both in vitro and in vivo. NUDT21, a core cleavage factor involved in APA, promoted the usage of proximal polyadenylation sites (PASs) on MZT1 mRNA by binding to the UGUA element located upstream of the proximal PAS. High percentage of distal polyA site usage index of MZT1 was significantly associated with a better prognosis. These findings demonstrate a crucial mechanism that NUDT21-mediated APA of MZT1 could promote the progression of PC. Our findings provided a better understanding of the connection between PC progression and APA machinery.
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Affiliation(s)
- Yu Zhou
- Department of Pancreatic Surgery, Department of General Surgery, Guangdong Provincial People’s Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, Guangdong Province, China
| | - Jiabin Yang
- Department of Pancreatic Surgery, Department of General Surgery, Guangdong Provincial People’s Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, Guangdong Province, China
- School of Medicine, South China University of Technology, Guangzhou, Guangdong Province, China
| | - Leyi Huang
- Department of Pancreatobiliary Surgery, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong Province, China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation Medical Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong Province, China
| | - Chao Liu
- Department of Pathology, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong Province, China
| | - Min Yu
- Department of Pancreatic Surgery, Department of General Surgery, Guangdong Provincial People’s Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, Guangdong Province, China
| | - Rufu Chen
- Department of Pancreatic Surgery, Department of General Surgery, Guangdong Provincial People’s Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, Guangdong Province, China
| | - Quanbo Zhou
- Department of Pancreatic Surgery, Department of General Surgery, Guangdong Provincial People’s Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, Guangdong Province, China
- Department of Pancreatobiliary Surgery, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong Province, China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation Medical Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong Province, China
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2
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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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3
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Haruta N, Sumiyoshi E, Honda Y, Terasawa M, Uchiyama C, Toya M, Kubota Y, Sugimoto A. A germline-specific role for unconventional components of the γ-tubulin complex in Caenorhabditis elegans. J Cell Sci 2023; 136:jcs260922. [PMID: 37313686 PMCID: PMC10657210 DOI: 10.1242/jcs.260922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 06/07/2023] [Indexed: 06/15/2023] Open
Abstract
The γ-tubulin complex (γTuC) is a widely conserved microtubule nucleator, but some of its components, namely GCP4, GCP5 and GCP6 (also known as TUBGCP4, TUBGCP5 and TUBGCP6, respectively), have not been detected in Caenorhabditis elegans. Here, we identified two γTuC-associated proteins in C. elegans, GTAP-1 and GTAP-2, for which apparent orthologs were detected only in the genus Caenorhabditis. GTAP-1 and GTAP-2 were found to localize at centrosomes and the plasma membrane of the germline, and their centrosomal localization was interdependent. In early C. elegans embryos, whereas the conserved γTuC component MZT-1 (also known as MOZART1 and MZT1) was essential for the localization of centrosomal γ-tubulin, depletion of GTAP-1 and/or GTAP-2 caused up to 50% reduction of centrosomal γ-tubulin and precocious disassembly of spindle poles during mitotic telophase. In the adult germline, GTAP-1 and GTAP-2 contributed to efficient recruitment of the γTuC to the plasma membrane. Depletion of GTAP-1, but not of GTAP-2, severely disrupted both the microtubule array and the honeycomb-like structure of the adult germline. We propose that GTAP-1 and GTAP-2 are unconventional components of the γTuC that contribute to the organization of both centrosomal and non-centrosomal microtubules by targeting the γTuC to specific subcellular sites in a tissue-specific manner.
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Affiliation(s)
- Nami Haruta
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Eisuke Sumiyoshi
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Yu Honda
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Masahiro Terasawa
- Laboratory for Developmental Genomics, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan
| | - Chihiro Uchiyama
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Mika Toya
- Laboratory for Developmental Genomics, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan
| | - Yukihiko Kubota
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Asako Sugimoto
- Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
- Laboratory for Developmental Genomics, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan
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4
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Shankar S, Hsu ZT, Ezquerra A, Li CC, Huang TL, Coyaud E, Viais R, Grauffel C, Raught B, Lim C, Lüders J, Tsai SY, Hsia KC. Α γ-tubulin complex-dependent pathway suppresses ciliogenesis by promoting cilia disassembly. Cell Rep 2022; 41:111642. [DOI: 10.1016/j.celrep.2022.111642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 08/30/2022] [Accepted: 10/19/2022] [Indexed: 11/18/2022] Open
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5
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Ramírez-Cota R, Espino-Vazquez AN, Carolina Rodriguez-Vega T, Evelyn Macias-Díaz R, Alicia Callejas-Negrete O, Freitag M, Fischer R, Roberson RW, Mouriño-Pérez RR. The cytoplasmic microtubule array in Neurospora crassa depends on microtubule-organizing centers at spindle pole bodies and microtubule +end-depending pseudo-MTOCs at septa. Fungal Genet Biol 2022; 162:103729. [DOI: 10.1016/j.fgb.2022.103729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 07/22/2022] [Accepted: 07/25/2022] [Indexed: 11/16/2022]
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6
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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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7
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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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8
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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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9
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Zimmermann F, Serna M, Ezquerra A, Fernandez-Leiro R, Llorca O, Luders J. Assembly of the asymmetric human γ-tubulin ring complex by RUVBL1-RUVBL2 AAA ATPase. SCIENCE ADVANCES 2020; 6:eabe0894. [PMID: 33355144 PMCID: PMC11206223 DOI: 10.1126/sciadv.abe0894] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 11/11/2020] [Indexed: 06/12/2023]
Abstract
The microtubule nucleator γ-tubulin ring complex (γTuRC) is essential for the function of microtubule organizing centers such as the centrosome. Since its discovery over two decades ago, γTuRC has evaded in vitro reconstitution and thus detailed structure-function studies. Here, we show that a complex of RuvB-like protein 1 (RUVBL1) and RUVBL2 "RUVBL" controls assembly and composition of γTuRC in human cells. Likewise, RUVBL assembles γTuRC from a minimal set of core subunits in a heterologous coexpression system. RUVBL interacts with γTuRC subcomplexes but is not part of fully assembled γTuRC. Purified, reconstituted γTuRC has nucleation activity and resembles native γTuRC as revealed by its cryo-electron microscopy (cryo-EM) structure at ~4.0-Å resolution. We further use cryo-EM to identify features that determine the intricate, higher-order γTuRC architecture. Our work finds RUVBL as an assembly factor that regulates γTuRC in cells and allows production of recombinant γTuRC for future in-depth mechanistic studies.
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Affiliation(s)
- 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
| | - Marina Serna
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain
| | - Artur Ezquerra
- 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
| | - Rafael Fernandez-Leiro
- 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 Luders
- 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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10
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Zupa E, Zheng A, Neuner A, Würtz M, Liu P, Böhler A, Schiebel E, Pfeffer S. The cryo-EM structure of a γ-TuSC elucidates architecture and regulation of minimal microtubule nucleation systems. Nat Commun 2020; 11:5705. [PMID: 33177498 PMCID: PMC7658347 DOI: 10.1038/s41467-020-19456-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 10/15/2020] [Indexed: 11/23/2022] Open
Abstract
The nucleation of microtubules from αβ-tubulin subunits is mediated by γ-tubulin complexes, which vary in composition across organisms. Aiming to understand how de novo microtubule formation is achieved and regulated by a minimal microtubule nucleation system, we here determined the cryo-electron microscopy structure of the heterotetrameric γ-tubulin small complex (γ-TuSC) from C. albicans at near-atomic resolution. Compared to the vertebrate γ-tubulin ring complex (γ-TuRC), we observed a vastly remodeled interface between the SPC/GCP-γ-tubulin spokes, which stabilizes the complex and defines the γ-tubulin arrangement. The relative positioning of γ-tubulin subunits indicates that a conformational rearrangement of the complex is required for microtubule nucleation activity, which follows opposing directionality as predicted for the vertebrate γ-TuRC. Collectively, our data suggest that the assembly and regulation mechanisms of γ-tubulin complexes fundamentally differ between the microtubule nucleation systems in lower and higher eukaryotes. The nucleation of microtubules from αβ-tubulin subunits is mediated by γtubulin complexes, which vary in composition across organisms. Here, authors present the cryo-EM structure of the heterotetrameric γ-tubulin small complex (γ-TuSC) from C. albicans at near-atomic resolution.
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Affiliation(s)
- Erik Zupa
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany
| | - Anjun Zheng
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany
| | - Annett Neuner
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany
| | - Martin Würtz
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany
| | - Peng Liu
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany
| | - Anna Böhler
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany
| | - Elmar Schiebel
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany.
| | - Stefan Pfeffer
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany.
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11
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Ma D, Han R. Microtubule organization defects in Arabidopsis thaliana. PLANT BIOLOGY (STUTTGART, GERMANY) 2020; 22:971-980. [PMID: 32215997 DOI: 10.1111/plb.13114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 03/12/2020] [Indexed: 05/15/2023]
Abstract
Microtubules (MT) are critical cytoskeletal filaments that have several functions in cell morphogenesis, cell division, vesicle transport and cytoplasmic separation in the spatiotemporal regulation of eukaryotic cells. Formation of MT requires the co-interaction of MT nucleation and α-β-tubulins, as well as MT-associated proteins (MAP). Many key MAP contributing to MT nucleation and elongation are essential for MT nucleation and regulation of MT dynamics, and are conserved in the plant kingdom. Therefore, the deletion or decrease of γ-tubulin ring complex (γTuRC) components and related MAP, such as the augmin complex, NEDD1, MZT1, EB1, MAP65, etc., in Arabidopsis thaliana results in MT organizational defects in the spindle and phragmoplast MT, as well as in chromosome defects. In addition, similar defects in MT organization and chromosome structure have been observed in plants under abiotic stress conditions, such as under high UV-B radiation. The MT can sense the signal from UV-B radiation, resulting in abnormal MT arrangement. Further studies are required to determine whether the abnormal chromosomes induced by UV-B radiation can be attributed to the involvement of abnormal MT arrays in chromosome migration after DNA damage.
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Affiliation(s)
- D Ma
- College of Life Science, Shanxi Normal University, Linfen, China
- Higher Education Key Laboratory of Plant Molecular and Environmental Stress Response (Shanxi Normal University) in Shanxi Province, Linfen, China
| | - R Han
- College of Life Science, Shanxi Normal University, Linfen, China
- Higher Education Key Laboratory of Plant Molecular and Environmental Stress Response (Shanxi Normal University) in Shanxi Province, Linfen, China
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12
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Promiscuous Binding of Microprotein Mozart1 to γ-Tubulin Complex Mediates Specific Subcellular Targeting to Control Microtubule Array Formation. Cell Rep 2020; 31:107836. [DOI: 10.1016/j.celrep.2020.107836] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 06/02/2020] [Accepted: 06/09/2020] [Indexed: 12/24/2022] Open
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13
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Gao X, Schmid M, Zhang Y, Fukuda S, Takeshita N, Fischer R. The spindle pole body of Aspergillus nidulans is asymmetrical and contains changing numbers of γ-tubulin complexes. J Cell Sci 2019; 132:jcs.234799. [PMID: 31740532 DOI: 10.1242/jcs.234799] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 10/28/2019] [Indexed: 12/14/2022] Open
Abstract
Centrosomes are important microtubule-organizing centers (MTOCs) in animal cells. In addition, non-centrosomal MTOCs (ncMTOCs) are found in many cell types. Their composition and structure are only poorly understood. Here, we analyzed nuclear MTOCs (spindle-pole bodies, SPBs) and septal MTOCs in Aspergillus nidulans They both contain γ-tubulin along with members of the family of γ-tubulin complex proteins (GCPs). Our data suggest that SPBs consist of γ-tubulin small complexes (γ-TuSCs) at the outer plaque, and larger γ-tubulin ring complexes (γ-TuRC) at the inner plaque. We show that the MztA protein, an ortholog of the human MOZART protein (also known as MZT1), interacted with the inner plaque receptor PcpA (the homolog of fission yeast Pcp1) at SPBs, while no interaction nor colocalization was detected between MztA and the outer plaque receptor ApsB (fission yeast Mto1). Septal MTOCs consist of γ-TuRCs including MztA but are anchored through AspB and Spa18 (fission yeast Mto2). MztA is not essential for viability, although abnormal spindles were observed frequently in cells lacking MztA. Quantitative PALM imaging revealed unexpected dynamics of the protein composition of SPBs, with changing numbers of γ-tubulin complexes over time during interphase and constant numbers during mitosis.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Xiaolei Gao
- Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Dept. of Microbiology, Fritz-Haber-Weg 4, D-76131 Karlsruhe, Germany
| | - Marjorie Schmid
- Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Dept. of Microbiology, Fritz-Haber-Weg 4, D-76131 Karlsruhe, Germany
| | - Ying Zhang
- Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Dept. of Microbiology, Fritz-Haber-Weg 4, D-76131 Karlsruhe, Germany
| | - Sayumi Fukuda
- Tsukuba University, Faculty of Life and Environmental Sciences, Tsukuba 305-8572, Japan
| | - Norio Takeshita
- Tsukuba University, Faculty of Life and Environmental Sciences, Tsukuba 305-8572, Japan
| | - Reinhard Fischer
- Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Dept. of Microbiology, Fritz-Haber-Weg 4, D-76131 Karlsruhe, Germany
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14
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Leong SL, Lynch EM, Zou J, Tay YD, Borek WE, Tuijtel MW, Rappsilber J, Sawin KE. Reconstitution of Microtubule Nucleation In Vitro Reveals Novel Roles for Mzt1. Curr Biol 2019; 29:2199-2207.e10. [PMID: 31287970 PMCID: PMC6616311 DOI: 10.1016/j.cub.2019.05.058] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 04/29/2019] [Accepted: 05/23/2019] [Indexed: 12/25/2022]
Abstract
Microtubule (MT) nucleation depends on the γ-tubulin complex (γ-TuC), in which multiple copies of the heterotetrameric γ-tubulin small complex (γ-TuSC) associate to form a ring-like structure (in metazoans, γ-tubulin ring complex; γ-TuRC) [1-7]. Additional conserved regulators of the γ-TuC include the small protein Mzt1 (MOZART1 in human; GIP1/1B and GIP2/1A in plants) [8-13] and proteins containing a Centrosomin Motif 1 (CM1) domain [10, 14-19]. Many insights into γ-TuC regulators have come from in vivo analysis in fission yeast Schizosaccharomyces pombe. The S. pombe CM1 protein Mto1 recruits the γ-TuC to microtubule-organizing centers (MTOCs) [14, 20-22], and analysis of Mto1[bonsai], a truncated version of Mto1 that cannot localize to MTOCs, has shown that Mto1 also has a role in γ-TuC activation [23]. S. pombe Mzt1 interacts with γ-TuSC and is essential for γ-TuC function and localization to MTOCs [11, 12]. However, the mechanisms by which Mzt1 functions remain unclear. Here we describe reconstitution of MT nucleation using purified recombinant Mto1[bonsai], the Mto1 partner protein Mto2, γ-TuSC, and Mzt1. Multiple copies of the six proteins involved coassemble to form a 34-40S ring-like "MGM" holocomplex that is a potent MT nucleator in vitro. Using purified MGM and subcomplexes, we investigate the role of Mzt1 in MT nucleation. Our results suggest that Mzt1 is critical to stabilize Alp6, the S. pombe homolog of human γ-TuSC protein GCP3, in an "interaction-competent" form within the γ-TuSC. This is essential for MGM to become a functional nucleator.
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Affiliation(s)
- Su Ling Leong
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Eric M Lynch
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Juan Zou
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Ye Dee Tay
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Weronika E Borek
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Maarten W Tuijtel
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Juri Rappsilber
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK; Chair of Bioanalytics, Institute of Biotechnology, Technische Universität Berlin, Berlin 13355, Germany
| | - Kenneth E Sawin
- Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh EH9 3BF, UK.
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15
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Abstract
Microtubules are major constituents of the cytoskeleton in all eukaryotic cells. They are essential for chromosome segregation during cell division, for directional intracellular transport and for building specialized cellular structures such as cilia or flagella. Their assembly has to be controlled spatially and temporally. For this, the cell uses multiprotein complexes containing γ-tubulin. γ-Tubulin has been found in two different types of complexes, γ-tubulin small complexes and γ-tubulin ring complexes. Binding to adaptors and activator proteins transforms these complexes into structural templates that drive the nucleation of new microtubules in a highly controlled manner. This review discusses recent advances on the mechanisms of assembly, recruitment and activation of γ-tubulin complexes at microtubule-organizing centres.
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Affiliation(s)
- Dorian Farache
- Centre de Biologie Intégrative, Centre de Biologie du Développement, CNRS-Université Toulouse III, 31062 Toulouse, France
| | - Laurent Emorine
- Centre de Biologie Intégrative, Centre de Biologie du Développement, CNRS-Université Toulouse III, 31062 Toulouse, France
| | - Laurence Haren
- Centre de Biologie Intégrative, Centre de Biologie du Développement, CNRS-Université Toulouse III, 31062 Toulouse, France
| | - Andreas Merdes
- Centre de Biologie Intégrative, Centre de Biologie du Développement, CNRS-Université Toulouse III, 31062 Toulouse, France
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16
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Shen J, Li T, Niu X, Liu W, Zheng S, Wang J, Wang F, Cao X, Yao X, Zheng F, Fu C. The J-domain cochaperone Rsp1 interacts with Mto1 to organize noncentrosomal microtubule assembly. Mol Biol Cell 2019; 30:256-267. [PMID: 30427751 PMCID: PMC6589567 DOI: 10.1091/mbc.e18-05-0279] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Microtubule biogenesis initiates at various intracellular sites, including the centrosome, the Golgi apparatus, the nuclear envelope, and preexisting microtubules. Similarly, in the fission yeast Schizosaccharomyces pombe, interphase microtubules are nucleated at the spindle pole body (SPB), the nuclear envelope, and preexisting microtubules, depending on Mto1 activity. Despite the essential role of Mto1 in promoting microtubule nucleation, how distribution of Mto1 in different sites is regulated has remained elusive. Here, we show that the J-domain cochaperone Rsp1 interacts with Mto1 and specifies the localization of Mto1 to non-SPB nucleation sites. The absence of Rsp1 abolishes the localization of Mto1 to non-SPB nucleation sites, with concomitant enrichment of Mto1 to the SPB and the nuclear envelope. In contrast, Rsp1 overexpression impairs the localization of Mto1 to all microtubule organization sites. These findings delineate a previously uncharacterized mechanism in which Rsp1-Mto1 interaction orchestrates non-SPB microtubule formation.
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Affiliation(s)
- Juan Shen
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei 230027, China
| | - Tianpeng Li
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei 230027, China
| | - Xiaojia Niu
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei 230027, China
| | - Wenyue Liu
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei 230027, China
| | - Shengnan Zheng
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei 230027, China
| | - Jing Wang
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei 230027, China
| | - Fengsong Wang
- School of Life Sciences, Anhui Medical University, Hefei, Anhui 230027, China
| | - Xinwang Cao
- School of Life Sciences, Anhui Medical University, Hefei, Anhui 230027, China
| | - Xuebiao Yao
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei 230027, China
| | - Fan Zheng
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei 230027, China
| | - Chuanhai Fu
- Division of Molecular and Cell Biophysics, Hefei National Science Center for Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Chinese Academy of Sciences Center for Excellence in Molecular Cell Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China.,Anhui Key Laboratory for Cellular Dynamics and Chemical Biology, University of Science and Technology of China, Hefei 230027, China
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17
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Microtubule nucleation by γ-tubulin complexes and beyond. Essays Biochem 2018; 62:765-780. [PMID: 30315097 PMCID: PMC6281477 DOI: 10.1042/ebc20180028] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2018] [Revised: 09/05/2018] [Accepted: 09/13/2018] [Indexed: 12/21/2022]
Abstract
In this short review, we give an overview of microtubule nucleation within cells. It is nearly 30 years since the discovery of γ-tubulin, a member of the tubulin superfamily essential for proper microtubule nucleation in all eukaryotes. γ-tubulin associates with other proteins to form multiprotein γ-tubulin ring complexes (γ-TuRCs) that template and catalyse the otherwise kinetically unfavourable assembly of microtubule filaments. These filaments can be dynamic or stable and they perform diverse functions, such as chromosome separation during mitosis and intracellular transport in neurons. The field has come a long way in understanding γ-TuRC biology but several important and unanswered questions remain, and we are still far from understanding the regulation of microtubule nucleation in a multicellular context. Here, we review the current literature on γ-TuRC assembly, recruitment, and activation and discuss the potential importance of γ-TuRC heterogeneity, the role of non-γ-TuRC proteins in microtubule nucleation, and whether γ-TuRCs could serve as good drug targets for cancer therapy.
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18
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Sallee MD, Zonka JC, Skokan TD, Raftrey BC, Feldman JL. Tissue-specific degradation of essential centrosome components reveals distinct microtubule populations at microtubule organizing centers. PLoS Biol 2018; 16:e2005189. [PMID: 30080857 PMCID: PMC6103517 DOI: 10.1371/journal.pbio.2005189] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 08/21/2018] [Accepted: 07/20/2018] [Indexed: 11/19/2022] Open
Abstract
Non-centrosomal microtubule organizing centers (ncMTOCs) are found in most differentiated cells, but how these structures regulate microtubule organization and dynamics is largely unknown. We optimized a tissue-specific degradation system to test the role of the essential centrosomal microtubule nucleators γ-tubulin ring complex (γ-TuRC) and AIR-1/Aurora A at the apical ncMTOC, where they both localize in Caenorhabditis elegans embryonic intestinal epithelial cells. As at the centrosome, the core γ-TuRC component GIP-1/GCP3 is required to recruit other γ-TuRC components to the apical ncMTOC, including MZT-1/MZT1, characterized here for the first time in animal development. In contrast, AIR-1 and MZT-1 were specifically required to recruit γ-TuRC to the centrosome, but not to centrioles or to the apical ncMTOC. Surprisingly, microtubules remain robustly organized at the apical ncMTOC upon γ-TuRC and AIR-1 co-depletion, and upon depletion of other known microtubule regulators, including TPXL-1/TPX2, ZYG-9/ch-TOG, PTRN-1/CAMSAP, and NOCA-1/Ninein. However, loss of GIP-1 removed a subset of dynamic EBP-2/EB1-marked microtubules, and the remaining dynamic microtubules grew faster. Together, these results suggest that different microtubule organizing centers (MTOCs) use discrete proteins for their function, and that the apical ncMTOC is composed of distinct populations of γ-TuRC-dependent and -independent microtubules that compete for a limited pool of resources.
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Affiliation(s)
- Maria D. Sallee
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Jennifer C. Zonka
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Taylor D. Skokan
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Brian C. Raftrey
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Jessica L. Feldman
- Department of Biology, Stanford University, Stanford, California, United States of America
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19
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Tovey CA, Tubman CE, Hamrud E, Zhu Z, Dyas AE, Butterfield AN, Fyfe A, Johnson E, Conduit PT. γ-TuRC Heterogeneity Revealed by Analysis of Mozart1. Curr Biol 2018; 28:2314-2323.e6. [PMID: 29983314 PMCID: PMC6065531 DOI: 10.1016/j.cub.2018.05.044] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 04/06/2018] [Accepted: 05/16/2018] [Indexed: 12/13/2022]
Abstract
Microtubules are essential for various cell processes [1] and are nucleated by multi-protein γ-tubulin ring complexes (γ-TuRCs) at various microtubule organizing centers (MTOCs), including centrosomes [2-6]. Recruitment of γ-TuRCs to different MTOCs at different times influences microtubule array formation, but how this is regulated remains an open question. It also remains unclear whether all γ-TuRCs within the same organism have the same composition and how any potential heterogeneity might influence γ-TuRC recruitment. MOZART1 (Mzt1) was recently identified as a γ-TuRC component [7, 8] and is conserved in nearly all eukaryotes [6, 9]. Mzt1 has so far been studied in cultured human cells, yeast, and plants; its absence leads to failures in γ-TuRC recruitment and cell division, resulting in cell death [7, 9-15]. Mzt1 is small (∼8.5 kDa), binds directly to core γ-TuRC components [9, 10, 14, 15], and appears to mediate the interaction between γ-TuRCs and proteins that tether γ-TuRCs to MTOCs [9, 15]. Here, we use Drosophila to investigate the function of Mzt1 in a multicellular animal for the first time. Surprisingly, we find that Drosophila Mzt1 is expressed only in the testes and is present in γ-TuRCs recruited to basal bodies, but not to mitochondria, in developing sperm cells. mzt1 mutants are viable but have defects in basal body positioning and γ-TuRC recruitment to centriole adjuncts; sperm formation is affected and mutants display a rapid age-dependent decline in sperm motility and male fertility. Our results reveal that tissue-specific and MTOC-specific γ-TuRC heterogeneity exist in Drosophila and highlight the complexity of γ-TuRC recruitment in a multicellular animal.
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Affiliation(s)
- Corinne A Tovey
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Chloe E Tubman
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Eva Hamrud
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Zihan Zhu
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Anna E Dyas
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Andrew N Butterfield
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Alex Fyfe
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Errin Johnson
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Paul T Conduit
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
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20
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Riquelme M, Aguirre J, Bartnicki-García S, Braus GH, Feldbrügge M, Fleig U, Hansberg W, Herrera-Estrella A, Kämper J, Kück U, Mouriño-Pérez RR, Takeshita N, Fischer R. Fungal Morphogenesis, from the Polarized Growth of Hyphae to Complex Reproduction and Infection Structures. Microbiol Mol Biol Rev 2018; 82:e00068-17. [PMID: 29643171 PMCID: PMC5968459 DOI: 10.1128/mmbr.00068-17] [Citation(s) in RCA: 183] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Filamentous fungi constitute a large group of eukaryotic microorganisms that grow by forming simple tube-like hyphae that are capable of differentiating into more-complex morphological structures and distinct cell types. Hyphae form filamentous networks by extending at their tips while branching in subapical regions. Rapid tip elongation requires massive membrane insertion and extension of the rigid chitin-containing cell wall. This process is sustained by a continuous flow of secretory vesicles that depends on the coordinated action of the microtubule and actin cytoskeletons and the corresponding motors and associated proteins. Vesicles transport cell wall-synthesizing enzymes and accumulate in a special structure, the Spitzenkörper, before traveling further and fusing with the tip membrane. The place of vesicle fusion and growth direction are enabled and defined by the position of the Spitzenkörper, the so-called cell end markers, and other proteins involved in the exocytic process. Also important for tip extension is membrane recycling by endocytosis via early endosomes, which function as multipurpose transport vehicles for mRNA, septins, ribosomes, and peroxisomes. Cell integrity, hyphal branching, and morphogenesis are all processes that are largely dependent on vesicle and cytoskeleton dynamics. When hyphae differentiate structures for asexual or sexual reproduction or to mediate interspecies interactions, the hyphal basic cellular machinery may be reprogrammed through the synthesis of new proteins and/or the modification of protein activity. Although some transcriptional networks involved in such reprogramming of hyphae are well studied in several model filamentous fungi, clear connections between these networks and known determinants of hyphal morphogenesis are yet to be established.
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Affiliation(s)
- Meritxell Riquelme
- Department of Microbiology, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California, Mexico
| | - Jesús Aguirre
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
| | - Salomon Bartnicki-García
- Department of Microbiology, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California, Mexico
| | - Gerhard H Braus
- Department of Molecular Microbiology and Genetics and Goettingen Center for Molecular Biosciences (GZMB), University of Goettingen, Goettingen, Germany
| | - Michael Feldbrügge
- Institute for Microbiology, Heinrich Heine University Düsseldorf, Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
| | - Ursula Fleig
- Institute for Functional Genomics of Microorganisms, Heinrich Heine University Düsseldorf, Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
| | - Wilhelm Hansberg
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
| | - Alfredo Herrera-Estrella
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Irapuato, Mexico
| | - Jörg Kämper
- Karlsruhe Institute of Technology-South Campus, Institute for Applied Biosciences, Karlsruhe, Germany
| | - Ulrich Kück
- Ruhr University Bochum, Lehrstuhl für Allgemeine und Molekulare Botanik, Bochum, Germany
| | - Rosa R Mouriño-Pérez
- Department of Microbiology, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California, Mexico
| | - Norio Takeshita
- University of Tsukuba, Faculty of Life and Environmental Sciences, Tsukuba, Japan
| | - Reinhard Fischer
- Karlsruhe Institute of Technology-South Campus, Institute for Applied Biosciences, Karlsruhe, Germany
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21
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Jiang P, Zheng S, Lu L. Mitotic-Spindle Organizing Protein MztA Mediates Septation Signaling by Suppressing the Regulatory Subunit of Protein Phosphatase 2A-ParA in Aspergillus nidulans. Front Microbiol 2018; 9:988. [PMID: 29774021 PMCID: PMC5951981 DOI: 10.3389/fmicb.2018.00988] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 04/27/2018] [Indexed: 12/20/2022] Open
Abstract
The proper timing and positioning of cytokinesis/septation is crucial for hyphal growth and conidiation in Aspergillus nidulans. The septation initiation network (SIN) components are a conserved spindle pole body (SPB) localized signaling cascade and the terminal kinase complex SidB-MobA, which must localize on the SPB in this pathway to trigger septation/cytokinesis. The regulatory subunit of phosphatase PP2A-ParA has been identified to be a negative regulator capable of inactivating the SIN. However, little is known about how ParA regulates the SIN pathway and whether ParA regulates the septum formation process through affecting the SPB-localized SIN proteins. In this study, through RNA-Seq and genetic approaches, we identified a new positive septation regulator, a putative mitotic-spindle organizing protein and a yeast Mzt1 homolog MztA, which acts antagonistically toward PP2A-ParA to coordinately regulate the SPB-localized SIN proteins SidB-MobA during septation. These findings imply that regulators, phosphatase PP2A-ParA and MztA counteract the septation function probably through balancing the polymerization and depolymerization of microtubules at the SPB.
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Affiliation(s)
- Ping Jiang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Shujun Zheng
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Ling Lu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing, China
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22
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Cukier CD, Tourdes A, El-Mazouni D, Guillet V, Nomme J, Mourey L, Milon A, Merdes A, Gervais V. NMR secondary structure and interactions of recombinant human MOZART1 protein, a component of the gamma-tubulin complex. Protein Sci 2017; 26:2240-2248. [PMID: 28851027 PMCID: PMC5654863 DOI: 10.1002/pro.3282] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 08/17/2017] [Accepted: 08/17/2017] [Indexed: 12/02/2022]
Abstract
Mitotic‐spindle organizing protein associated with a ring of γ‐tubulin 1 (MOZART1) is an 8.5 kDa protein linked to regulation of γ‐tubulin ring complexes (γTuRCs), which are involved in nucleation of microtubules. Despite its small size, MOZART1 represents a challenging target for detailed characterization in vitro. We described herein a protocol for efficient production of recombinant human MOZART1 in Escherichia coli and assessed the properties of the purified protein using a combination of size exclusion chromatography coupled with multiangle light scattering (SEC‐MALS), dynamic light scattering (DLS), and nuclear magnetic resonance (NMR) experiments. MOZART1 forms heterogeneous oligomers in solution. We identified optimal detergent and buffer conditions for recording well resolved NMR experiments allowing nearly full protein assignment and identification of three distinct alpha‐helical structured regions. Finally, using NMR, we showed that MOZART1 interacts with the N‐terminus (residues 1–250) of GCP3 (γ‐tubulin complex protein 3). Our data illustrate the capacity of MOZART1 to form oligomers, promoting multiple contacts with a subset of protein partners in the context of microtubule nucleation.
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Affiliation(s)
- Cyprian D Cukier
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Audrey Tourdes
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Dounia El-Mazouni
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Valérie Guillet
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Julian Nomme
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Lionel Mourey
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Alain Milon
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Andreas Merdes
- Centre de Biologie du Développement, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Virginie Gervais
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
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23
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Cavanaugh AM, Jaspersen SL. Big Lessons from Little Yeast: Budding and Fission Yeast Centrosome Structure, Duplication, and Function. Annu Rev Genet 2017; 51:361-383. [PMID: 28934593 DOI: 10.1146/annurev-genet-120116-024733] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Centrosomes are a functionally conserved feature of eukaryotic cells that play an important role in cell division. The conserved γ-tubulin complex organizes spindle and astral microtubules, which, in turn, separate replicated chromosomes accurately into daughter cells. Like DNA, centrosomes are duplicated once each cell cycle. Although in some cell types it is possible for cell division to occur in the absence of centrosomes, these divisions typically result in defects in chromosome number and stability. In single-celled organisms such as fungi, centrosomes [known as spindle pole bodies (SPBs)] are essential for cell division. SPBs also must be inserted into the membrane because fungi undergo a closed mitosis in which the nuclear envelope (NE) remains intact. This poorly understood process involves events similar or identical to those needed for de novo nuclear pore complex assembly. Here, we review how analysis of fungal SPBs has advanced our understanding of centrosomes and NE events.
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Affiliation(s)
- Ann M Cavanaugh
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA;
| | - Sue L Jaspersen
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA; .,Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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24
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Zhang Y, Gao X, Manck R, Schmid M, Osmani AH, Osmani SA, Takeshita N, Fischer R. Microtubule-organizing centers of Aspergillus nidulans
are anchored at septa by a disordered protein. Mol Microbiol 2017; 106:285-303. [DOI: 10.1111/mmi.13763] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/03/2017] [Indexed: 01/21/2023]
Affiliation(s)
- Ying Zhang
- Department of Microbiology, Institute for Applied Biosciences; Karlsruhe Institute of Technology (KIT) - South Campus, Fritz-Haber-Weg 4; Karlsruhe D-76131 Germany
| | - Xiaolei Gao
- Department of Microbiology, Institute for Applied Biosciences; Karlsruhe Institute of Technology (KIT) - South Campus, Fritz-Haber-Weg 4; Karlsruhe D-76131 Germany
| | - Raphael Manck
- Department of Microbiology, Institute for Applied Biosciences; Karlsruhe Institute of Technology (KIT) - South Campus, Fritz-Haber-Weg 4; Karlsruhe D-76131 Germany
| | - Marjorie Schmid
- Department of Microbiology, Institute for Applied Biosciences; Karlsruhe Institute of Technology (KIT) - South Campus, Fritz-Haber-Weg 4; Karlsruhe D-76131 Germany
| | - Aysha H. Osmani
- Department of Molecular Genetics; Ohio State University, 105 Biological Sciences Building, 484 W 12th Ave; Columbus OH 43210 USA
| | - Stephen A. Osmani
- Department of Molecular Genetics; Ohio State University, 105 Biological Sciences Building, 484 W 12th Ave; Columbus OH 43210 USA
| | - Norio Takeshita
- Department of Microbiology, Institute for Applied Biosciences; Karlsruhe Institute of Technology (KIT) - South Campus, Fritz-Haber-Weg 4; Karlsruhe D-76131 Germany
- School of Life and Environmental Sciences; University of Tsukuba; Ten-Nou-Dai Tsukuba 305-8572 Japan
| | - Reinhard Fischer
- Department of Microbiology, Institute for Applied Biosciences; Karlsruhe Institute of Technology (KIT) - South Campus, Fritz-Haber-Weg 4; Karlsruhe D-76131 Germany
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25
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Fal K, Asnacios A, Chabouté ME, Hamant O. Nuclear envelope: a new frontier in plant mechanosensing? Biophys Rev 2017; 9:389-403. [PMID: 28801801 PMCID: PMC5578935 DOI: 10.1007/s12551-017-0302-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 07/28/2017] [Indexed: 02/07/2023] Open
Abstract
In animals, it is now well established that forces applied at the cell surface are propagated through the cytoskeleton to the nucleus, leading to deformations of the nuclear structure and, potentially, to modification of gene expression. Consistently, altered nuclear mechanics has been related to many genetic disorders, such as muscular dystrophy, cardiomyopathy and progeria. In plants, the integration of mechanical signals in cell and developmental biology has also made great progress. Yet, while the link between cell wall stresses and cytoskeleton is consolidated, such cortical mechanical cues have not been integrated with the nucleoskeleton. Here, we propose to take inspiration from studies on animal nuclei to identify relevant methods amenable to probing nucleus mechanics and deformation in plant cells, with a focus on microrheology. To identify potential molecular targets, we also compare the players at the nuclear envelope, namely lamina and LINC complex, in both plant and animal nuclei. Understanding how mechanical signals are transduced to the nucleus across kingdoms will likely have essential implications in development (e.g. how mechanical cues add robustness to gene expression patterns), in the nucleoskeleton-cytoskeleton nexus (e.g. how stress is propagated in turgid/walled cells), as well as in transcriptional control, chromatin biology and epigenetics.
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Affiliation(s)
- Kateryna Fal
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, 69342, Lyon, France
| | - Atef Asnacios
- Laboratoire Matières et Systèmes Complexes, Université Paris-Diderot and CNRS, UMR 7057, Sorbonne Paris Cité, Paris, France
| | - Marie-Edith Chabouté
- Institut de Biologie Moléculaire des Plantes, CNRS, Université de Strasbourg, 67000, Strasbourg, France
| | - Olivier Hamant
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, 69342, Lyon, France.
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26
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Chen JV, Buchwalter RA, Kao LR, Megraw TL. A Splice Variant of Centrosomin Converts Mitochondria to Microtubule-Organizing Centers. Curr Biol 2017; 27:1928-1940.e6. [PMID: 28669756 DOI: 10.1016/j.cub.2017.05.090] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 05/02/2017] [Accepted: 05/31/2017] [Indexed: 11/25/2022]
Abstract
Non-centrosomal microtubule organizing centers (MTOCs) direct microtubule (MT) organization to exert diverse cell-type-specific functions. In Drosophila spermatids, the giant mitochondria provide structural platforms for MT reorganization to support elongation of the extremely long sperm. However, the molecular basis for this mitochondrial MTOC and other non-centrosomal MTOCs has not been discerned. Here we report that Drosophila centrosomin (cnn) expresses two major protein variants: the centrosomal form (CnnC) and a non-centrosomal form in testes (CnnT). CnnC is established as essential for functional centrosomes, the major MTOCs in animal cells. We show that CnnT is expressed exclusively in testes by alternative splicing and localizes to giant mitochondria in spermatids. In cell culture, CnnT targets to the mitochondrial surface, recruits the MT nucleator γ-tubulin ring complex (γ-TuRC), and is sufficient to convert mitochondria to MTOCs independent of core pericentriolar proteins that regulate MT assembly at centrosomes. We mapped two separate domains in CnnT: one that is necessary and sufficient to target it to mitochondria and another that is necessary and sufficient to recruit γ-TuRCs and nucleate MTs. In elongating spermatids, CnnT forms speckles on the giant mitochondria that are required to recruit γ-TuRCs to organize MTs and support spermiogenesis. This molecular characterization of the mitochondrial MTOC defines a minimal molecular requirement for MTOC generation and implicates the potent role of Cnn (or its related) proteins in the direct regulation of MT assembly and organization of non-centrosomal MTOCs.
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Affiliation(s)
- Jieyan V Chen
- Department of Biomedical Sciences, Florida State University, 1115 West Call Street, Tallahassee, FL 32306, USA.
| | - Rebecca A Buchwalter
- Department of Biomedical Sciences, Florida State University, 1115 West Call Street, Tallahassee, FL 32306, USA
| | - Ling-Rong Kao
- Department of Biomedical Sciences, Florida State University, 1115 West Call Street, Tallahassee, FL 32306, USA
| | - Timothy L Megraw
- Department of Biomedical Sciences, Florida State University, 1115 West Call Street, Tallahassee, FL 32306, USA.
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27
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Bestul AJ, Yu Z, Unruh JR, Jaspersen SL. Molecular model of fission yeast centrosome assembly determined by superresolution imaging. J Cell Biol 2017; 216:2409-2424. [PMID: 28619713 PMCID: PMC5551712 DOI: 10.1083/jcb.201701041] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 04/17/2017] [Accepted: 05/10/2017] [Indexed: 01/06/2023] Open
Abstract
Microtubule-organizing centers (MTOCs), known as centrosomes in animals and spindle pole bodies (SPBs) in fungi, are important for the faithful distribution of chromosomes between daughter cells during mitosis as well as for other cellular functions. The cytoplasmic duplication cycle and regulation of the Schizosaccharomyces pombe SPB is analogous to centrosomes, making it an ideal model to study MTOC assembly. Here, we use superresolution structured illumination microscopy with single-particle averaging to localize 14 S. pombe SPB components and regulators, determining both the relationship of proteins to each other within the SPB and how each protein is assembled into a new structure during SPB duplication. These data enabled us to build the first comprehensive molecular model of the S. pombe SPB, resulting in structural and functional insights not ascertained through investigations of individual subunits, including functional similarities between Ppc89 and the budding yeast SPB scaffold Spc42, distribution of Sad1 to a ring-like structure and multiple modes of Mto1 recruitment.
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Affiliation(s)
| | - Zulin Yu
- Stowers Institute for Medical Research, Kansas City, MO
| | - Jay R Unruh
- Stowers Institute for Medical Research, Kansas City, MO
| | - Sue L Jaspersen
- Stowers Institute for Medical Research, Kansas City, MO .,Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS
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28
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Sulimenko V, Hájková Z, Klebanovych A, Dráber P. Regulation of microtubule nucleation mediated by γ-tubulin complexes. PROTOPLASMA 2017; 254:1187-1199. [PMID: 28074286 DOI: 10.1007/s00709-016-1070-z] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 12/22/2016] [Indexed: 05/18/2023]
Abstract
The microtubule cytoskeleton is critically important for spatio-temporal organization of eukaryotic cells. The nucleation of new microtubules is typically restricted to microtubule organizing centers (MTOCs) and requires γ-tubulin that assembles into multisubunit complexes of various sizes. γ-Tubulin ring complexes (TuRCs) are efficient microtubule nucleators and are associated with large number of targeting, activating and modulating proteins. γ-Tubulin-dependent nucleation of microtubules occurs both from canonical MTOCs, such as spindle pole bodies and centrosomes, and additional sites such as Golgi apparatus, nuclear envelope, plasma membrane-associated sites, chromatin and surface of pre-existing microtubules. Despite many advances in structure of γ-tubulin complexes and characterization of γTuRC interacting factors, regulatory mechanisms of microtubule nucleation are not fully understood. Here, we review recent work on the factors and regulatory mechanisms that are involved in centrosomal and non-centrosomal microtubule nucleation.
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Affiliation(s)
- Vadym Sulimenko
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Zuzana Hájková
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Anastasiya Klebanovych
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Pavel Dráber
- Department of Biology of Cytoskeleton, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague 4, Czech Republic.
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29
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Lin TC, Neuner A, Flemming D, Liu P, Chinen T, Jäkle U, Arkowitz R, Schiebel E. MOZART1 and γ-tubulin complex receptors are both required to turn γ-TuSC into an active microtubule nucleation template. J Cell Biol 2016; 215:823-840. [PMID: 27920216 PMCID: PMC5166503 DOI: 10.1083/jcb.201606092] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 10/03/2016] [Accepted: 11/04/2016] [Indexed: 01/14/2023] Open
Abstract
Cells use γ-tubulin complex to nucleate microtubules. The assembly of active microtubule nucleator is spatially and temporally regulated through the cell cycle. Lin et al. show that the protein Mzt1/MOZART1 and γ-tubulin complex receptors directly interact and act together to assemble the γ-tubulin small complex into an active microtubule nucleation template and that such interaction is conserved between Candida albicans and human cells. MOZART1/Mzt1 is required for the localization of γ-tubulin complexes to microtubule (MT)–organizing centers from yeast to human cells. Nevertheless, the molecular function of MOZART1/Mzt1 is largely unknown. Taking advantage of the minimal MT nucleation system of Candida albicans, we reconstituted the interactions of Mzt1, γ-tubulin small complex (γ-TuSC), and γ-tubulin complex receptors (γ-TuCRs) Spc72 and Spc110 in vitro. With affinity measurements, domain deletion, and swapping, we show that Spc110 and Mzt1 bind to distinct regions of the γ-TuSC. In contrast, both Mzt1 and γ-TuSC interact with the conserved CM1 motif of Spc110/Spc72. Spc110/Spc72 and Mzt1 constitute “oligomerization chaperones,” cooperatively promoting and directing γ-TuSC oligomerization into MT nucleation-competent rings. Consistent with the functions of Mzt1, human MOZART1 directly interacts with the CM1-containing region of the γ-TuCR CEP215. MOZART1 depletion in human cells destabilizes the large γ-tubulin ring complex and abolishes CEP215CM1-induced ectopic MT nucleation. Together, we reveal conserved functions of MOZART1/Mzt1 through interactions with γ-tubulin complex subunits and γ-TuCRs.
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Affiliation(s)
- Tien-Chen Lin
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH-Allianz, 69120 Heidelberg, Germany
| | - Annett Neuner
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH-Allianz, 69120 Heidelberg, Germany
| | | | - Peng Liu
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH-Allianz, 69120 Heidelberg, Germany
| | - Takumi Chinen
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH-Allianz, 69120 Heidelberg, Germany
| | - Ursula Jäkle
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH-Allianz, 69120 Heidelberg, Germany
| | - Robert Arkowitz
- Université Côte d'Azur, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut de Biologie Valrose, 06108 Nice, France
| | - Elmar Schiebel
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH-Allianz, 69120 Heidelberg, Germany
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30
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Farache D, Jauneau A, Chemin C, Chartrain M, Rémy MH, Merdes A, Haren L. Functional Analysis of γ-Tubulin Complex Proteins Indicates Specific Lateral Association via Their N-terminal Domains. J Biol Chem 2016; 291:23112-23125. [PMID: 27660388 DOI: 10.1074/jbc.m116.744862] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Indexed: 11/06/2022] Open
Abstract
Microtubules are nucleated from multiprotein complexes containing γ-tubulin and associated γ-tubulin complex proteins (GCPs). Small complexes (γTuSCs) comprise two molecules of γ-tubulin bound to the C-terminal domains of GCP2 and GCP3. γTuSCs associate laterally into helical structures, providing a structural template for microtubule nucleation. In most eukaryotes γTuSCs associate with additional GCPs (4, 5, and 6) to form the core of the so-called γ-tubulin ring complex (γTuRC). GCPs 2-6 constitute a family of homologous proteins. Previous structural analysis and modeling of GCPs suggest that all family members can potentially integrate into the helical structure. Here we provide experimental evidence for this model. Using chimeric proteins in which the N- and C-terminal domains of different GCPs are swapped, we show that the N-terminal domains define the functional identity of GCPs, whereas the C-terminal domains are exchangeable. FLIM-FRET experiments indicate that GCP4 and GCP5 associate laterally within the complex, and their interaction is mediated by their N-terminal domains as previously shown for γTuSCs. Our results suggest that all GCPs are incorporated into the helix via lateral interactions between their N-terminal domains, whereas the C-terminal domains mediate longitudinal interactions with γ-tubulin. Moreover, we show that binding to γ-tubulin is not essential for integrating into the helical complex.
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Affiliation(s)
- Dorian Farache
- From the Centre de Biologie du Développement, CNRS-Université Toulouse III, 31062 Toulouse, France and
| | - Alain Jauneau
- Plateforme Imagerie-Microscopie, FR 3450 Pôle de Biotechnologie Végétale, 31326 Castanet-Tolosan, France
| | - Cécile Chemin
- From the Centre de Biologie du Développement, CNRS-Université Toulouse III, 31062 Toulouse, France and
| | - Marine Chartrain
- From the Centre de Biologie du Développement, CNRS-Université Toulouse III, 31062 Toulouse, France and
| | - Marie-Hélène Rémy
- From the Centre de Biologie du Développement, CNRS-Université Toulouse III, 31062 Toulouse, France and
| | - Andreas Merdes
- From the Centre de Biologie du Développement, CNRS-Université Toulouse III, 31062 Toulouse, France and
| | - Laurence Haren
- From the Centre de Biologie du Développement, CNRS-Université Toulouse III, 31062 Toulouse, France and
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31
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Masuda H, Toda T. Synergistic role of fission yeast Alp16GCP6 and Mzt1MOZART1 in γ-tubulin complex recruitment to mitotic spindle pole bodies and spindle assembly. Mol Biol Cell 2016; 27:1753-63. [PMID: 27053664 PMCID: PMC4884066 DOI: 10.1091/mbc.e15-08-0577] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 03/23/2016] [Accepted: 03/29/2016] [Indexed: 11/30/2022] Open
Abstract
In fission yeast, γ-tubulin ring complex (γTuRC)-specific components Gfh1(GCP4), Mod21(GCP5), and Alp16(GCP6) are nonessential for cell growth. Of these deletion mutants, only alp16Δ shows synthetic lethality with temperature-sensitive mutants of Mzt1(MOZART1), a component of the γTuRC required for recruitment of the complex to microtubule-organizing centers. γ-Tubulin small complex levels at mitotic spindle pole bodies (SPBs, the centrosome equivalent in fungi) and microtubule levels for preanaphase spindles are significantly reduced in alp16Δ cells but not in gfh1Δ or mod21Δ cells. Furthermore, alp16Δ cells often form monopolar spindles and frequently lose a minichromosome when the spindle assembly checkpoint is inactivated. Alp16(GCP6) promotes Mzt1-dependent γTuRC recruitment to mitotic SPBs and enhances spindle microtubule assembly in a manner dependent on its expression levels. Gfh1(GCP4) and Mod21(GCP5) are not required for Alp16(GCP6)-dependent γTuRC recruitment. Mzt1 has an additional role in the activation of the γTuRC for spindle microtubule assembly. The ratio of Mzt1 to γTuRC levels for preanaphase spindles is higher than at other stages of the cell cycle. Mzt1 overproduction enhances spindle microtubule assembly without affecting γTuRC levels at mitotic SPBs. We propose that Alp16(GCP6) and Mzt1 act synergistically for efficient bipolar spindle assembly to ensure faithful chromosome segregation.
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Affiliation(s)
- Hirohisa Masuda
- Lincoln's Inn Fields Laboratory, The Francis Crick Institute, London WC2A 3LY, United Kingdom
| | - Takashi Toda
- Lincoln's Inn Fields Laboratory, The Francis Crick Institute, London WC2A 3LY, United Kingdom Hiroshima Research Center for Healthy Aging, Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
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32
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Abstract
Microtubules mediate important cellular processes by forming highly ordered arrays. Organization of these networks is achieved by nucleating and anchoring microtubules at centrosomes and other structures collectively known as microtubule-organizing centers (MTOCs). However, the diverse microtubule configurations found in different cell types may not be generated and maintained by MTOCs alone. Work over the last few years has revealed a mechanism that has the capacity to generate cell-type-specific microtubule arrays independently of a specific organizer: nucleation of microtubules from the lateral surface of pre-existing microtubules. This type of nucleation requires cooperation between two different multi-subunit protein complexes, augmin and the γ-tubulin ring complex (γTuRC). Here we review recent molecular insight into microtubule-dependent nucleation and discuss the possibility that the augmin-γTuRC module, initially described in mitosis, may broadly contribute to microtubule organization also in non-mitotic cells.
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Affiliation(s)
- Carlos Sánchez-Huertas
- Institute for Research in Biomedicine (IRB Barcelona), C/ Baldiri Reixac 10, Barcelona, Spain
| | - Jens Lüders
- Institute for Research in Biomedicine (IRB Barcelona), C/ Baldiri Reixac 10, Barcelona, Spain.
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33
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Cota RR, Teixidó-Travesa N, Ezquerra A, Eibes S, Lacasa C, Roig J, Lüders J. MZT1 regulates microtubule nucleation by linking γTuRC assembly to adapter-mediated targeting and activation. J Cell Sci 2016; 130:406-419. [DOI: 10.1242/jcs.195321] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 11/09/2016] [Indexed: 01/22/2023] Open
Abstract
Regulation of the γ-tubulin ring complex (γTuRC) through targeting and activation restricts nucleation of microtubules to microtubule organizing centers (MTOCs), aiding in the assembly of ordered microtubule arrays. However, the mechanistic basis of this important regulation remains poorly understood. Here we show that in human cells γTuRC integrity, determined by the presence of γ-tubulin complex proteins (GCPs) 2-6, is a prerequisite for interaction with the targeting factor NEDD1, impacting on essentially all γ-tubulin dependent functions. Recognition of γTuRC integrity is mediated by MZT1, which binds not only to the GCP3 subunit as previously shown, but cooperatively also to other GCPs through a conserved hydrophobic motif present in the N-termini of GCP2, GCP3, GCP5, and GCP6. MZT1 knockdown causes severe cellular defects under conditions that leave γTuRC intact, suggesting that the essential function of MZT1 is not in γTuRC assembly. Instead, MZT1 specifically binds fully assembled γTuRC to enable interaction with NEDD1 for targeting, and with the CM1 domain of CDK5RAP2 for stimulating nucleation activity. Thus, MZT1 is a ‘priming factor’ for the γTuRC that allows spatial regulation of nucleation.
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Affiliation(s)
- Rosa Ramírez Cota
- Institute for Research in Biomedicine (IRB Barcelona), 08028 Barcelona, Spain
| | | | - Artur Ezquerra
- Institute for Research in Biomedicine (IRB Barcelona), 08028 Barcelona, Spain
| | - Susana Eibes
- Institute for Research in Biomedicine (IRB Barcelona), 08028 Barcelona, Spain
| | - Cristina Lacasa
- Institute for Research in Biomedicine (IRB Barcelona), 08028 Barcelona, Spain
| | - Joan Roig
- Institute for Research in Biomedicine (IRB Barcelona), 08028 Barcelona, Spain
- Molecular Biology Institute of Barcelona (IBMB-CSIC), 08028 Barcelona, Spain
| | - Jens Lüders
- Institute for Research in Biomedicine (IRB Barcelona), 08028 Barcelona, Spain
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34
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Arabidopsis MZT1 homologs GIP1 and GIP2 are essential for centromere architecture. Proc Natl Acad Sci U S A 2015; 112:8656-60. [PMID: 26124146 DOI: 10.1073/pnas.1506351112] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Centromeres play a pivotal role in maintaining genome integrity by facilitating the recruitment of kinetochore and sister-chromatid cohesion proteins, both required for correct chromosome segregation. Centromeres are epigenetically specified by the presence of the histone H3 variant (CENH3). In this study, we investigate the role of the highly conserved γ-tubulin complex protein 3-interacting proteins (GIPs) in Arabidopsis centromere regulation. We show that GIPs form a complex with CENH3 in cycling cells. GIP depletion in the gip1gip2 knockdown mutant leads to a decreased CENH3 level at centromeres, despite a higher level of Mis18BP1/KNL2 present at both centromeric and ectopic sites. We thus postulate that GIPs are required to ensure CENH3 deposition and/or maintenance at centromeres. In addition, the recruitment at the centromere of other proteins such as the CENP-C kinetochore component and the cohesin subunit SMC3 is impaired in gip1gip2. These defects in centromere architecture result in aneuploidy due to severely altered centromeric cohesion. Altogether, we ascribe a central function to GIPs for the proper recruitment and/or stabilization of centromeric proteins essential in the specification of the centromere identity, as well as for centromeric cohesion in somatic cells.
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35
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Targeting of γ-tubulin complexes to microtubule organizing centers: conservation and divergence. Trends Cell Biol 2015; 25:296-307. [DOI: 10.1016/j.tcb.2014.12.002] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 11/25/2014] [Accepted: 12/01/2014] [Indexed: 11/29/2022]
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36
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Abstract
Microtubules (MTs) are highly conserved polar polymers that are key elements of the eukaryotic cytoskeleton and are essential for various cell functions. αβ-tubulin, a heterodimer containing one structural GTP and one hydrolysable and exchangeable GTP, is the building block of MTs and is formed by the sequential action of several molecular chaperones. GTP hydrolysis in the MT lattice is mechanistically coupled with MT growth, thus giving MTs a metastable and dynamic nature. MTs adopt several distinct higher-order organizations that function in cell division and cell morphogenesis. Small molecular weight compounds that bind tubulin are used as herbicides and as research tools to investigate MT functions in plant cells. The de novo formation of MTs in cells requires conserved γ-tubulin-containing complexes and targeting/activating regulatory proteins that contribute to the geometry of MT arrays. Various MT regulators and tubulin modifications control the dynamics and organization of MTs throughout the cell cycle and in response to developmental and environmental cues. Signaling pathways that converge on the regulation of versatile MT functions are being characterized.
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Affiliation(s)
- Takashi Hashimoto
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Takayama 8916-5, Ikoma, Nara 630-0192, Japan
- Address correspondence to
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37
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Lin TC, Neuner A, Schlosser YT, Scharf AND, Weber L, Schiebel E. Cell-cycle dependent phosphorylation of yeast pericentrin regulates γ-TuSC-mediated microtubule nucleation. eLife 2014; 3:e02208. [PMID: 24842996 PMCID: PMC4034690 DOI: 10.7554/elife.02208] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Budding yeast Spc110, a member of γ-tubulin complex receptor family (γ-TuCR), recruits γ-tubulin complexes to microtubule (MT) organizing centers (MTOCs). Biochemical studies suggest that Spc110 facilitates higher-order γ-tubulin complex assembly (Kollman et al., 2010). Nevertheless the molecular basis for this activity and the regulation are unclear. Here we show that Spc110 phosphorylated by Mps1 and Cdk1 activates γ-TuSC oligomerization and MT nucleation in a cell cycle dependent manner. Interaction between the N-terminus of the γ-TuSC subunit Spc98 and Spc110 is important for this activity. Besides the conserved CM1 motif in γ-TuCRs (Sawin et al., 2004), a second motif that we named Spc110/Pcp1 motif (SPM) is also important for MT nucleation. The activating Mps1 and Cdk1 sites lie between SPM and CM1 motifs. Most organisms have both SPM-CM1 (Spc110/Pcp1/PCNT) and CM1-only (Spc72/Mto1/Cnn/CDK5RAP2/myomegalin) types of γ-TuCRs. The two types of γ-TuCRs contain distinct but conserved C-terminal MTOC targeting domains. DOI:http://dx.doi.org/10.7554/eLife.02208.001 Microtubules are hollow structures made of proteins that have a central role in cell division and a variety of other important processes within cells. For a cell to divide successfully, the chromosomes containing the genetic information of the cell must be duplicated and then separated so that one copy of each chromosome ends up in each daughter cell. To separate the chromosomes, microtubules extend out from two structures called spindle pole bodies, which are found at either end of the cell, and pull one copy of each chromosome to opposite sides of the cell. Although the individual proteins that make up a microtubule can self-assemble into tubes, this occurs very slowly, so cells employ other molecules to speed up this process. In yeast cells, a protein called gamma-tubulin is recruited to the spindle pole body by the protein Spc110, where it combines with two other proteins to form a complex called the gamma-tubulin small complex. Several of these complexes then join together to form a ring, which probably acts as the platform that microtubules grow from. Recent observations suggested that Spc110 may help to construct this ring, but without revealing how. Now, Lin et al. reveal that Spc110 can regulate microtubule formation by controlling how several gamma-tubulin small complexes bind together, and have identified the exact section of Spc110 that interacts with the complexes. However, the Spc110 must become active before it can perform this role, and it is only activated during certain stages of cell division, through phosphorylation. The structures in Spc110 that bind to the gamma-tubulin small complex in yeast are also found in gamma-tubulin binding receptor proteins in human cells. The work of Lin et al. demonstrates that proteins that are assumed to have passive roles within cells, such as Spc110, often play more active roles instead. DOI:http://dx.doi.org/10.7554/eLife.02208.002
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Affiliation(s)
- Tien-Chen Lin
- Zentrum für Molekulare Biologie (ZMBH), Universität Heidelberg, Heidelberg, Germany The Hartmut Hoffmann-Berling International Graduate School, University of Heidelberg, Heidelberg, Germany
| | - Annett Neuner
- Zentrum für Molekulare Biologie (ZMBH), Universität Heidelberg, Heidelberg, Germany
| | - Yvonne T Schlosser
- Zentrum für Molekulare Biologie (ZMBH), Universität Heidelberg, Heidelberg, Germany
| | - Annette N D Scharf
- Zentrum für Molekulare Biologie (ZMBH), Universität Heidelberg, Heidelberg, Germany
| | - Lisa Weber
- Zentrum für Molekulare Biologie (ZMBH), Universität Heidelberg, Heidelberg, Germany
| | - Elmar Schiebel
- Zentrum für Molekulare Biologie (ZMBH), Universität Heidelberg, Heidelberg, Germany
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Batzenschlager M, Herzog E, Houlné G, Schmit AC, Chabouté ME. GIP/MZT1 proteins orchestrate nuclear shaping. FRONTIERS IN PLANT SCIENCE 2014; 5:29. [PMID: 24570680 PMCID: PMC3916773 DOI: 10.3389/fpls.2014.00029] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 01/22/2014] [Indexed: 05/28/2023]
Abstract
The functional organization of the nuclear envelope (NE) is only just emerging in plants with the recent characterization of NE protein complexes and their molecular links to the actin cytoskeleton. The NE also plays a role in microtubule nucleation by recruiting γ-Tubulin Complexes (γ-TuCs) which contribute to the establishment of a robust mitotic spindle. γ-tubulin Complex Protein 3 (GCP3)-interacting proteins (GIPs) have been identified recently as integral components of γ-TuCs. GIPs have been conserved throughout evolution and are also named MZT1 (mitotic-spindle organizing protein 1). This review focuses on recent data investigating the role of GIP/MZT1 at the NE, including insights from the study of GIP partners. It also uncovers new functions for GIP/MZT1 during interphase and highlights a current view of NE-associated components which are critical for nuclear shaping during both cell division and differentiation.
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Affiliation(s)
| | | | | | - Anne-Catherine Schmit
- *Correspondence: Anne-Catherine Schmit, Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, UPR 2357, 12 rue du Gl Zimmer, 67084 Strasbourg, France e-mail:
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Batzenschlager M, Masoud K, Janski N, Houlné G, Herzog E, Evrard JL, Baumberger N, Erhardt M, Nominé Y, Kieffer B, Schmit AC, Chabouté ME. The GIP gamma-tubulin complex-associated proteins are involved in nuclear architecture in Arabidopsis thaliana. FRONTIERS IN PLANT SCIENCE 2013; 4:480. [PMID: 24348487 PMCID: PMC3842039 DOI: 10.3389/fpls.2013.00480] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 11/05/2013] [Indexed: 05/08/2023]
Abstract
During interphase, the microtubular cytoskeleton of cycling plant cells is organized in both cortical and perinuclear arrays. Perinuclear microtubules (MTs) are nucleated from γ-Tubulin Complexes (γ-TuCs) located at the surface of the nucleus. The molecular mechanisms of γ-TuC association to the nuclear envelope (NE) are currently unknown. The γ-TuC Protein 3 (GCP3)-Interacting Protein 1 (GIP1) is the smallest γ-TuC component identified so far. AtGIP1 and its homologous protein AtGIP2 participate in the localization of active γ-TuCs at interphasic and mitotic MT nucleation sites. Arabidopsis gip1gip2 mutants are impaired in establishing a fully functional mitotic spindle and exhibit severe developmental defects. In this study, gip1gip2 knock down mutants were further characterized at the cellular level. In addition to defects in both the localization of γ-TuC core proteins and MT fiber robustness, gip1gip2 mutants exhibited a severe alteration of the nuclear shape associated with an abnormal distribution of the nuclear pore complexes. Simultaneously, they showed a misorganization of the inner nuclear membrane protein AtSUN1. Furthermore, AtGIP1 was identified as an interacting partner of AtTSA1 which was detected, like the AtGIP proteins, at the NE. These results provide the first evidence for the involvement of a γ-TuC component in both nuclear shaping and NE organization. Functional hypotheses are discussed in order to propose a model for a GIP-dependent nucleo-cytoplasmic continuum.
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Affiliation(s)
- Morgane Batzenschlager
- Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire des Plantes, UPR 2357, Conventionné avec l'Université de StrasbourgStrasbourg, France
| | - Kinda Masoud
- Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire des Plantes, UPR 2357, Conventionné avec l'Université de StrasbourgStrasbourg, France
| | - Natacha Janski
- Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire des Plantes, UPR 2357, Conventionné avec l'Université de StrasbourgStrasbourg, France
| | - Guy Houlné
- Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire des Plantes, UPR 2357, Conventionné avec l'Université de StrasbourgStrasbourg, France
| | - Etienne Herzog
- Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire des Plantes, UPR 2357, Conventionné avec l'Université de StrasbourgStrasbourg, France
| | - Jean-Luc Evrard
- Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire des Plantes, UPR 2357, Conventionné avec l'Université de StrasbourgStrasbourg, France
| | - Nicolas Baumberger
- Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire des Plantes, UPR 2357, Conventionné avec l'Université de StrasbourgStrasbourg, France
| | - Mathieu Erhardt
- Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire des Plantes, UPR 2357, Conventionné avec l'Université de StrasbourgStrasbourg, France
| | - Yves Nominé
- Biotechnologie et Signalisation cellulaire, Institut de Recherche de l'Ecole de Biotechnologie de Strasbourg, UMR 7242, Université de StrasbourgIllkirch, France
| | - Bruno Kieffer
- Institut de Génétique et Biologie Moléculaire et Cellulaire, Ecole Supérieure de Biotechnologie de StrasbourgIllkirch, France
| | - Anne-Catherine Schmit
- Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire des Plantes, UPR 2357, Conventionné avec l'Université de StrasbourgStrasbourg, France
- *Correspondence: Anne-Catherine Schmit, Institut de Biologie Moléculaire des Plantes, UPR2357 du CNRS, 12, rue du Gl Zimmer, 67084 Strasbourg-Cedex, France e-mail:
| | - Marie-Edith Chabouté
- Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire des Plantes, UPR 2357, Conventionné avec l'Université de StrasbourgStrasbourg, France
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