1
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Pena GE, Zhou X, Slevin L, Brownlee C, Heald R. The NLS3 Motif in TPX2 Regulates Spindle Architecture in Xenopus Egg Extracts. Cytoskeleton (Hoboken) 2025. [PMID: 40326229 DOI: 10.1002/cm.22034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2024] [Revised: 04/08/2025] [Accepted: 04/16/2025] [Indexed: 05/07/2025]
Abstract
A bipolar spindle composed of microtubules and many associated proteins functions to segregate chromosomes during cell division in all eukaryotes, yet both spindle size and architecture vary dramatically across different species and cell types. Targeting protein for Xklp2 (TPX2) is one candidate factor for modulating spindle microtubule organization through its roles in branching microtubule nucleation, activation of the mitotic kinase Aurora A, and association with the kinesin-5 (Eg5) motor. Here we characterize a conserved nuclear localization sequence (NLS) motif, 123KKLK126 in Xenopus laevis TPX2, which regulates astral microtubule formation and spindle pole morphology in Xenopus egg extracts. Addition of recombinant TPX2 with this sequence mutated to AALA stimulated spontaneous formation of microtubule asters and increased recruitment of phosphorylated Aurora A, pericentrin, and Eg5 to meiotic spindle poles while still binding to the regulatory transport factor importin α. We propose that TPX2 is a linchpin spindle assembly factor whose regulation contributes to the activation of multiple microtubule polymerizing and organizing proteins, generating distinct spindle architectures.
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Affiliation(s)
- Guadalupe E Pena
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
| | - Xiao Zhou
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
- AbbVie, South San Francisco, California, USA
| | - Lauren Slevin
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
- Swedish Maternal and Fetal Specialty Center, Seattle, Washington, USA
| | - Christopher Brownlee
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
- Deparment of Pharmacological Sciences, Stony Brook University, Stony Brook, New York, USA
| | - Rebecca Heald
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
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2
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Duan D, Koleske AJ. Phase separation of microtubule-binding proteins - implications for neuronal function and disease. J Cell Sci 2024; 137:jcs263470. [PMID: 39679446 PMCID: PMC11795294 DOI: 10.1242/jcs.263470] [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] [Indexed: 12/17/2024] Open
Abstract
Protein liquid-liquid phase separation (LLPS) is driven by intrinsically disordered regions and multivalent binding domains, both of which are common features of diverse microtubule (MT) regulators. Many in vitro studies have dissected the mechanisms by which MT-binding proteins (MBPs) regulate MT nucleation, stabilization and dynamics, and investigated whether LLPS plays a role in these processes. However, more recent in vivo studies have focused on how MBP LLPS affects biological functions throughout neuronal development. Dysregulation of MBP LLPS can lead to formation of aggregates - an underlying feature in many neurodegenerative diseases - such as the tau neurofibrillary tangles present in Alzheimer's disease. In this Review, we highlight progress towards understanding the regulation of MT dynamics through the lens of phase separation of MBPs and associated cytoskeletal regulators, from both in vitro and in vivo studies. We also discuss how LLPS of MBPs regulates neuronal development and maintains homeostasis in mature neurons.
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Affiliation(s)
- Daisy Duan
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06510, USA
| | - Anthony J. Koleske
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06510, USA
- Department of Neuroscience, Yale University, New Haven, CT 06510, USA
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3
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Yue W, Zhang HY, Schatten H, Meng TG, Sun QY. CtIP regulates G2/M transition and bipolar spindle assembly during mouse oocyte meiosis. J Genet Genomics 2024; 51:1435-1446. [PMID: 39277031 DOI: 10.1016/j.jgg.2024.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2024] [Revised: 09/04/2024] [Accepted: 09/05/2024] [Indexed: 09/17/2024]
Abstract
CtBP-interacting protein (CtIP) is known for its multifaceted roles in DNA repair and genomic stability, directing the homologous recombination-mediated DNA double-stranded break repair pathway via DNA end resection, an essential error-free repair process vital for genome stability. Mammalian oocytes are highly prone to DNA damage accumulation due to prolonged G2/prophase arrest. Here, we explore the functions of CtIP in meiotic cell cycle regulation via a mouse oocyte model. Depletion of CtIP by siRNA injection results in delayed germinal vesicle breakdown and failed polar body extrusion. Mechanistically, CtIP deficiency increases DNA damage and decreases the expression and nuclear entry of CCNB1, resulting in marked impairment of meiotic resumption, which can be rescued by exogenous CCNB1 overexpression. Furthermore, depletion of CtIP disrupts microtubule-organizing centers coalescence at spindle poles as indicated by failed accumulation of γ-tubulin, p-Aurora kinase A, Kif2A, and TPX2, leading to abnormal spindle assembly and prometaphase arrest. These results provide valuable insights into the important roles of CtIP in the G2/M checkpoint and spindle assembly in mouse oocyte meiotic cell cycle regulation.
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Affiliation(s)
- Wei Yue
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Hong-Yong Zhang
- Zhanjiang Institute of Clinical Medicine, Central People's Hospital of Zhanjiang, Guangdong Medical University Zhanjiang Central Hospital, Zhanjiang, Guangdong 524045, China
| | - Heide Schatten
- Department of Veterinary Pathobiology, University of Missouri, Columbia, MO 65211, USA
| | - Tie-Gang Meng
- Guangzhou Key Laboratory of Metabolic Diseases and Reproductive Health, Guangdong-Hong Kong Metabolism & Reproduction Joint Laboratory, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou, Guangdong 510317, China
| | - Qing-Yuan Sun
- Guangzhou Key Laboratory of Metabolic Diseases and Reproductive Health, Guangdong-Hong Kong Metabolism & Reproduction Joint Laboratory, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou, Guangdong 510317, China.
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4
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Cantwell H, Nguyen H, Kettenbach A, Heald R. Spindle morphology changes between meiosis and mitosis driven by CK2 regulation of the Ran pathway. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.25.605073. [PMID: 39211121 PMCID: PMC11361180 DOI: 10.1101/2024.07.25.605073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
The transition from meiotic divisions in the oocyte to embryonic mitoses is a critical step in animal development. Despite negligible changes to cell size and shape, following fertilization the small, barrel-shaped meiotic spindle is replaced by a large zygotic spindle that nucleates abundant astral microtubules at spindle poles. To probe underlying mechanisms, we applied a drug screening approach using Ciona eggs and found that inhibition of Casein Kinase 2 (CK2) caused a shift from meiotic to mitotic-like spindle morphology with nucleation of robust astral microtubules, an effect reproduced in cytoplasmic extracts prepared from Xenopus eggs. In both species, CK2 activity decreased at fertilization. Phosphoproteomic differences between Xenopus meiotic and mitotic extracts that also accompanied CK2 inhibition pointed to RanGTP-regulated factors as potential targets. Interfering with RanGTP-driven microtubule formation suppressed astral microtubule growth caused by CK2 inhibition. These data support a model in which CK2 activity attenuation at fertilization leads to activation of RanGTP-regulated microtubule effectors that induce mitotic spindle morphology.
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5
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Chen YJ, Tseng SC, Chen PT, Hwang E. The non-mitotic role of HMMR in regulating the localization of TPX2 and the dynamics of microtubules in neurons. eLife 2024; 13:RP94547. [PMID: 38904660 PMCID: PMC11192530 DOI: 10.7554/elife.94547] [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] [Indexed: 06/22/2024] Open
Abstract
A functional nervous system is built upon the proper morphogenesis of neurons to establish the intricate connection between them. The microtubule cytoskeleton is known to play various essential roles in this morphogenetic process. While many microtubule-associated proteins (MAPs) have been demonstrated to participate in neuronal morphogenesis, the function of many more remains to be determined. This study focuses on a MAP called HMMR in mice, which was originally identified as a hyaluronan binding protein and later found to possess microtubule and centrosome binding capacity. HMMR exhibits high abundance on neuronal microtubules and altering the level of HMMR significantly affects the morphology of neurons. Instead of confining to the centrosome(s) like cells in mitosis, HMMR localizes to microtubules along axons and dendrites. Furthermore, transiently expressing HMMR enhances the stability of neuronal microtubules and increases the formation frequency of growing microtubules along the neurites. HMMR regulates the microtubule localization of a non-centrosomal microtubule nucleator TPX2 along the neurite, offering an explanation for how HMMR contributes to the promotion of growing microtubules. This study sheds light on how cells utilize proteins involved in mitosis for non-mitotic functions.
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Affiliation(s)
- Yi-Ju Chen
- Institute of Molecular Medicine and Bioengineering, National Yang Ming Chiao Tung UniversityHsinchuTaiwan
| | - Shun-Cheng Tseng
- Department of Orthopedic Surgery, Changhua Christian HospitalChanghuaTaiwan
- Department of Biological Science and Technology, National Yang Ming Chiao Tung UniversityHsinchuTaiwan
| | - Peng-Tzu Chen
- Institute of Molecular Medicine and Bioengineering, National Yang Ming Chiao Tung UniversityHsinchuTaiwan
| | - Eric Hwang
- Institute of Molecular Medicine and Bioengineering, National Yang Ming Chiao Tung UniversityHsinchuTaiwan
- Department of Biological Science and Technology, National Yang Ming Chiao Tung UniversityHsinchuTaiwan
- Institute of Bioinformatics and Systems Biology, National Yang Ming Chiao Tung UniversityHsinchuTaiwan
- Center for Intelligent Drug Systems and Smart Bio-devices (IDS2B), National Yang Ming Chiao Tung UniversityHsinchuTaiwan
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6
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Zheng H, Zhang Q, Liu X, Shi F, Yang F, Xiang S, Jiang H. Aurora-A condensation mediated by BuGZ aids its mitotic centrosome functions. iScience 2024; 27:109785. [PMID: 38746663 PMCID: PMC11090908 DOI: 10.1016/j.isci.2024.109785] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Revised: 12/30/2023] [Accepted: 04/16/2024] [Indexed: 03/17/2025] Open
Abstract
Centrosomes composed of centrioles and the pericentriolar material (PCM), serve as the platform for microtubule polymerization during mitosis. Despite some centriole and PCM proteins have been reported to utilize liquid-liquid phase separation (LLPS) to perform their mitotic functions, whether and how centrosomal kinases exert the coacervation in mitosis is still unknown. Here we reveal that Aurora-A, one key centrosomal kinase in regulating centrosome formation and functions, undergoes phase separation in vitro or in centrosomes from prophase, mediated by the conserved positive-charged residues inside its intrinsic disordered region (IDR) and the intramolecular interaction between its N- and C-terminus. Aurora-A condensation affects centrosome maturation, separation, initial spindle formation from the spindle pole and its kinase activity. Moreover, BuGZ interacts with Aurora-A to enhance its LLPS and centrosome functions. Thus, we propose that Aurora-A collaborates with BuGZ to exhibit the property of LLPS in centrosomes to control its centrosome-dependent functions from prophase.
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Affiliation(s)
- Hui Zheng
- Laboratory for Aging and Cancer Research, Frontiers Science Center Disease-related Molecular Network, State Key Laboratory of Respiratory Health and Multimorbidity and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610041, Sichuan, China
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
| | - Qiaoqiao Zhang
- Laboratory for Aging and Cancer Research, Frontiers Science Center Disease-related Molecular Network, State Key Laboratory of Respiratory Health and Multimorbidity and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610041, Sichuan, China
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
| | - Xing Liu
- MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Center for Cross-disciplinary Sciences, University of Science & Technology of China, School of Life Sciences, Hefei, China
| | - Fan Shi
- MOE Key Lab for Cellular Dynamics, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Fengrui Yang
- MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Center for Cross-disciplinary Sciences, University of Science & Technology of China, School of Life Sciences, Hefei, China
| | - Shengqi Xiang
- MOE Key Lab for Cellular Dynamics, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
| | - Hao Jiang
- Laboratory for Aging and Cancer Research, Frontiers Science Center Disease-related Molecular Network, State Key Laboratory of Respiratory Health and Multimorbidity and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610041, Sichuan, China
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7
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Rodrigues JS, Chenlo M, Bravo SB, Perez-Romero S, Suarez-Fariña M, Sobrino T, Sanz-Pamplona R, González-Prieto R, Blanco Freire MN, Nogueiras R, López M, Fugazzola L, Cameselle-Teijeiro JM, Alvarez CV. dsRNAi-mediated silencing of PIAS2beta specifically kills anaplastic carcinomas by mitotic catastrophe. Nat Commun 2024; 15:3736. [PMID: 38744818 PMCID: PMC11094195 DOI: 10.1038/s41467-024-47751-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 04/11/2024] [Indexed: 05/16/2024] Open
Abstract
The E3 SUMO ligase PIAS2 is expressed at high levels in differentiated papillary thyroid carcinomas but at low levels in anaplastic thyroid carcinomas (ATC), an undifferentiated cancer with high mortality. We show here that depletion of the PIAS2 beta isoform with a transcribed double-stranded RNA-directed RNA interference (PIAS2b-dsRNAi) specifically inhibits growth of ATC cell lines and patient primary cultures in vitro and of orthotopic patient-derived xenografts (oPDX) in vivo. Critically, PIAS2b-dsRNAi does not affect growth of normal or non-anaplastic thyroid tumor cultures (differentiated carcinoma, benign lesions) or cell lines. PIAS2b-dsRNAi also has an anti-cancer effect on other anaplastic human cancers (pancreas, lung, and gastric). Mechanistically, PIAS2b is required for proper mitotic spindle and centrosome assembly, and it is a dosage-sensitive protein in ATC. PIAS2b depletion promotes mitotic catastrophe at prophase. High-throughput proteomics reveals the proteasome (PSMC5) and spindle cytoskeleton (TUBB3) to be direct targets of PIAS2b SUMOylation at mitotic initiation. These results identify PIAS2b-dsRNAi as a promising therapy for ATC and other aggressive anaplastic carcinomas.
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Affiliation(s)
- Joana S Rodrigues
- Neoplasia & Endocrine Differentiation, Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), University of Santiago de Compostela (USC), Instituto de Investigación Sanitaria (IDIS), Santiago de Compostela, Spain
- Dana Farber Cancer Institute, Boston, MA, USA
| | - Miguel Chenlo
- Neoplasia & Endocrine Differentiation, Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), University of Santiago de Compostela (USC), Instituto de Investigación Sanitaria (IDIS), Santiago de Compostela, Spain
| | - Susana B Bravo
- Department of Proteomics, Complejo Hospitalario Universitario de Santiago de Compostela (CHUS), Servicio Galego de Saúde (SERGAS), Instituto de Investigación Sanitaria de Santiago (IDIS), University of Santiago de Compostela (USC), Santiago de Compostela, Spain
| | - Sihara Perez-Romero
- Neoplasia & Endocrine Differentiation, Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), University of Santiago de Compostela (USC), Instituto de Investigación Sanitaria (IDIS), Santiago de Compostela, Spain
| | - Maria Suarez-Fariña
- Neoplasia & Endocrine Differentiation, Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), University of Santiago de Compostela (USC), Instituto de Investigación Sanitaria (IDIS), Santiago de Compostela, Spain
| | - Tomas Sobrino
- Department of NeuroAging Group - Clinical Neurosciences Research Laboratory (LINC), Complejo Hospitalario Universitario de Santiago de Compostela (CHUS), Servicio Galego de Saúde (SERGAS), Instituto de Investigación Sanitaria de Santiago (IDIS), University of Santiago de Compostela (USC), Santiago de Compostela, Spain
- Centro de Investigación Biomédica en Red en Enfermedades Neurodegenerativas, Instituto de Salud Carlos III, 28029, Madrid, Spain
| | - Rebeca Sanz-Pamplona
- University Hospital Lozano Blesa, Institute for Health Research Aragon (IISA), ARAID Foundation, Aragon Government and CIBERESP, Zaragoza, Spain
- Centro de Investigación Biomédica en Red en Epidemiología y Salud Pública, Instituto de Salud Carlos III, 28029, Madrid, Spain
| | - Román González-Prieto
- Cell Dynamics and Signaling Department, Andalusian Center for Molecular Biology and Regenerative Medicine, Universidad de Sevilla - CSIC - Universidad Pablo de Olavide-Junta de Andalucía, 41092, Sevilla, Spain
- Department of Cell Biology, Faculty of Biology, University of Sevilla, 41012, Sevilla, Spain
| | - Manuel Narciso Blanco Freire
- Department of Surgery, Complejo Hospitalario Universitario de Santiago de Compostela (CHUS), Servicio Galego de Saúde (SERGAS), Instituto de Investigación Sanitaria de Santiago (IDIS), University of Santiago de Compostela (USC), Santiago de Compostela, Spain
| | - Ruben Nogueiras
- Molecular Metabolism, Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), University of Santiago de Compostela (USC), Instituto de Investigación Sanitaria (IDIS), Santiago de Compostela, Spain
| | - Miguel López
- NeurObesity, Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), University of Santiago de Compostela (USC), Instituto de Investigación Sanitaria (IDIS), Santiago de Compostela, Spain
| | - Laura Fugazzola
- Department of Endocrine and Metabolic Diseases and Laboratory of Endocrine and Metabolic Research, Istituto Auxologico Italiano, Istituto Di Ricovero e Cura a Carattere Scientifico (IRCCS); Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - José Manuel Cameselle-Teijeiro
- Department of Pathology, Complejo Hospitalario Universitario de Santiago de Compostela (CHUS), Servicio Galego de Saúde (SERGAS), Instituto de Investigación Sanitaria de Santiago (IDIS), University of Santiago de Compostela (USC), Santiago de Compostela, Spain.
| | - Clara V Alvarez
- Neoplasia & Endocrine Differentiation, Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), University of Santiago de Compostela (USC), Instituto de Investigación Sanitaria (IDIS), Santiago de Compostela, Spain.
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8
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Pena GE, Zhou X, Slevin L, Brownlee C, Heald R. Identification of a motif in TPX2 that regulates spindle architecture in Xenopus egg extracts. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.10.579770. [PMID: 38370704 PMCID: PMC10871311 DOI: 10.1101/2024.02.10.579770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
A bipolar spindle composed of microtubules and many associated proteins functions to segregate chromosomes during cell division in all eukaryotes, yet spindle size and architecture varies dramatically across different species and cell types. Targeting protein for Xklp2 (TPX2) is one candidate factor for modulating spindle microtubule organization through its roles in branching microtubule nucleation, activation of the mitotic kinase Aurora A, and association with the kinesin-5 (Eg5) motor. Here we identify a conserved nuclear localization sequence (NLS) motif, 123 KKLK 126 in X. laevis TPX2, which regulates astral microtubule formation and spindle pole morphology in Xenopus egg extracts. Addition of recombinant TPX2 with this sequence mutated to AALA dramatically increased spontaneous formation of microtubule asters and recruitment of phosphorylated Aurora A, pericentrin, and Eg5 to meiotic spindle poles. We propose that TPX2 is a linchpin spindle assembly factor whose regulation contributes to the recruitment and activation of multiple microtubule polymerizing and organizing proteins, generating distinct spindle architectures.
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9
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Tian Q, Xie X, Lai R, Cheng C, Zhang Z, Chen Y, XuHan X, Lin Y, Lai Z. Functional and Transcriptome Analysis Reveal Specific Roles of Dimocarpus longan DlRan3A and DlRan3B in Root Hair Development, Reproductive Growth, and Stress Tolerance. PLANTS (BASEL, SWITZERLAND) 2024; 13:480. [PMID: 38498444 PMCID: PMC10891736 DOI: 10.3390/plants13040480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 01/29/2024] [Accepted: 02/05/2024] [Indexed: 03/20/2024]
Abstract
Ran GTPases play essential roles in plant growth and development. Our previous studies revealed the nuclear localization of DlRan3A and DlRan3B proteins and proposed their functional redundancy and distinction in Dimocarpus longan somatic embryogenesis, hormone, and abiotic stress responses. To further explore the possible roles of DlRan3A and DlRan3B, gene expression analysis by qPCR showed that their transcripts were both more abundant in the early embryo and pulp in longan. Heterologous expression of DlRan3A driven by its own previously cloned promoter led to stunted growth, increased root hair density, abnormal fruits, bigger seeds, and enhanced abiotic stress tolerance. Conversely, constitutive promoter CaMV 35S (35S)-driven expression of DlRan3A, 35S, or DlRan3B promoter-controlled expression of DlRan3B did not induce the alterations in growth phenotype, while they rendered different hypersensitivities to abiotic stresses. Based on the transcriptome profiling of longan Ran overexpression in tobacco plants, we propose new mechanisms of the Ran-mediated regulation of genes associated with cell wall biosynthesis and expansion. Also, the transgenic plants expressing DlRan3A or DlRan3B genes controlled by 35S or by their own promoter all exhibited altered mRNA levels of stress-related and transcription factor genes. Moreover, DlRan3A overexpressors were more tolerant to salinity, osmotic, and heat stresses, accompanied by upregulation of oxidation-related genes, possibly involving the Ran-RBOH-CIPK network. Analysis of a subset of selected genes from the Ran transcriptome identified possible cold stress-related roles of brassinosteroid (BR)-responsive genes. The marked presence of genes related to cell wall biosynthesis and expansion, hormone, and defense responses highlighted their close regulatory association with Ran.
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Affiliation(s)
- Qilin Tian
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.T.); (X.X.); (R.L.); (C.C.); (Z.Z.); (Y.C.); (X.X.); (Y.L.)
| | - Xiying Xie
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.T.); (X.X.); (R.L.); (C.C.); (Z.Z.); (Y.C.); (X.X.); (Y.L.)
- School of Media and Design, Nantong Institute of Technology, Nantong 226019, China
| | - Ruilian Lai
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.T.); (X.X.); (R.L.); (C.C.); (Z.Z.); (Y.C.); (X.X.); (Y.L.)
| | - Chunzhen Cheng
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.T.); (X.X.); (R.L.); (C.C.); (Z.Z.); (Y.C.); (X.X.); (Y.L.)
| | - Zihao Zhang
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.T.); (X.X.); (R.L.); (C.C.); (Z.Z.); (Y.C.); (X.X.); (Y.L.)
| | - Yukun Chen
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.T.); (X.X.); (R.L.); (C.C.); (Z.Z.); (Y.C.); (X.X.); (Y.L.)
| | - Xu XuHan
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.T.); (X.X.); (R.L.); (C.C.); (Z.Z.); (Y.C.); (X.X.); (Y.L.)
- Institut de la Recherche Interdisciplinaire de Toulouse, IRIT-ARI, 31300 Toulouse, France
| | - Yuling Lin
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.T.); (X.X.); (R.L.); (C.C.); (Z.Z.); (Y.C.); (X.X.); (Y.L.)
| | - Zhongxiong Lai
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.T.); (X.X.); (R.L.); (C.C.); (Z.Z.); (Y.C.); (X.X.); (Y.L.)
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10
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Kiyomitsu A, Nishimura T, Hwang SJ, Ansai S, Kanemaki MT, Tanaka M, Kiyomitsu T. Ran-GTP assembles a specialized spindle structure for accurate chromosome segregation in medaka early embryos. Nat Commun 2024; 15:981. [PMID: 38302485 PMCID: PMC10834446 DOI: 10.1038/s41467-024-45251-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Accepted: 01/19/2024] [Indexed: 02/03/2024] Open
Abstract
Despite drastic cellular changes during cleavage, a mitotic spindle assembles in each blastomere to accurately segregate duplicated chromosomes. Mechanisms of mitotic spindle assembly have been extensively studied using small somatic cells. However, mechanisms of spindle assembly in large vertebrate embryos remain little understood. Here, we establish functional assay systems in medaka (Oryzias latipes) embryos by combining CRISPR knock-in with auxin-inducible degron technology. Live imaging reveals several unexpected features of microtubule organization and centrosome positioning that achieve rapid, accurate cleavage. Importantly, Ran-GTP assembles a dense microtubule network at the metaphase spindle center that is essential for chromosome segregation in early embryos. This unique spindle structure is remodeled into a typical short, somatic-like spindle after blastula stages, when Ran-GTP becomes dispensable for chromosome segregation. We propose that despite the presence of centrosomes, the chromosome-derived Ran-GTP pathway has essential roles in functional spindle assembly in large, rapidly dividing vertebrate early embryos, similar to acentrosomal spindle assembly in oocytes.
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Affiliation(s)
- Ai Kiyomitsu
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan
| | - Toshiya Nishimura
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan
- Hokkaido University Fisheries Sciences, 3-1-1, Minato-cho, Hakodate, Hokkaido, 041-8611, Japan
| | - Shiang Jyi Hwang
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan
| | - Satoshi Ansai
- Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi, 980-8577, Japan
- Laboratory of Genome Editing Breeding, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, 606-8507, Japan
| | - Masato T Kanemaki
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems (ROIS), and Graduate Institute for Advanced Studies, SOKENDAI, Yata 1111, Mishima, Shizuoka, 411-8540, Japan
- Department of Biological Science, The University of Tokyo, Tokyo, 113-0033, Japan
| | - Minoru Tanaka
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan
| | - Tomomi Kiyomitsu
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan.
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11
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Scrofani J, Ruhnow F, Chew WX, Normanno D, Nedelec F, Surrey T, Vernos I. Branched microtubule nucleation and dynein transport organize RanGTP asters in Xenopus laevis egg extract. Mol Biol Cell 2024; 35:ar12. [PMID: 37991893 PMCID: PMC10881172 DOI: 10.1091/mbc.e23-10-0407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 11/03/2023] [Accepted: 11/07/2023] [Indexed: 11/24/2023] Open
Abstract
Chromosome segregation relies on the correct assembly of a bipolar spindle. Spindle pole self-organization requires dynein-dependent microtubule (MT) transport along other MTs. However, during M-phase RanGTP triggers MT nucleation and branching generating polarized arrays with nonastral organization in which MT minus ends are linked to the sides of other MTs. This raises the question of how branched-MT nucleation and dynein-mediated transport cooperate to organize the spindle poles. Here, we used RanGTP-dependent MT aster formation in Xenopus laevis (X. laevis) egg extract to study the interplay between these two seemingly conflicting organizing principles. Using temporally controlled perturbations of MT nucleation and dynein activity, we found that branched MTs are not static but instead dynamically redistribute over time as poles self-organize. Our experimental data together with computer simulations suggest a model where dynein together with dynactin and NuMA directly pulls and move branched MT minus ends toward other MT minus ends.
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Affiliation(s)
- Jacopo Scrofani
- Quantitative Cell Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain
| | - Felix Ruhnow
- Quantitative Cell Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain
| | - Wei-Xiang Chew
- Quantitative Cell Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain
| | - Davide Normanno
- Quantitative Cell Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain
| | - Francois Nedelec
- Sainsbury Laboratory, Cambridge University, Bateman street, CB2 1LR Cambridge, UK
| | - Thomas Surrey
- Quantitative Cell Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain
- Universitat Pompeu Fabra (UPF), 08002 Barcelona, Spain
- Institución Catalana de Investigación y Estudios Avanzados (ICREA), Pg. Lluis Companys 23, 08010 Barcelona, Spain
| | - Isabelle Vernos
- Quantitative Cell Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain
- Universitat Pompeu Fabra (UPF), 08002 Barcelona, Spain
- Institución Catalana de Investigación y Estudios Avanzados (ICREA), Pg. Lluis Companys 23, 08010 Barcelona, Spain
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12
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Guo C, Alfaro-Aco R, Zhang C, Russell RW, Petry S, Polenova T. Structural basis of protein condensation on microtubules underlying branching microtubule nucleation. Nat Commun 2023; 14:3682. [PMID: 37344496 PMCID: PMC10284871 DOI: 10.1038/s41467-023-39176-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 06/01/2023] [Indexed: 06/23/2023] Open
Abstract
Targeting protein for Xklp2 (TPX2) is a key factor that stimulates branching microtubule nucleation during cell division. Upon binding to microtubules (MTs), TPX2 forms condensates via liquid-liquid phase separation, which facilitates recruitment of microtubule nucleation factors and tubulin. We report the structure of the TPX2 C-terminal minimal active domain (TPX2α5-α7) on the microtubule lattice determined by magic-angle-spinning NMR. We demonstrate that TPX2α5-α7 forms a co-condensate with soluble tubulin on microtubules and binds to MTs between two adjacent protofilaments and at the intersection of four tubulin heterodimers. These interactions stabilize the microtubules and promote the recruitment of tubulin. Our results reveal that TPX2α5-α7 is disordered in solution and adopts a folded structure on MTs, indicating that TPX2α5-α7 undergoes structural changes from unfolded to folded states upon binding to microtubules. The aromatic residues form dense interactions in the core, which stabilize folding of TPX2α5-α7 on microtubules. This work informs on how the phase-separated TPX2α5-α7 behaves on microtubules and represents an atomic-level structural characterization of a protein that is involved in a condensate on cytoskeletal filaments.
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Affiliation(s)
- Changmiao Guo
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Raymundo Alfaro-Aco
- Department of Molecular Biology, Princeton University, Princeton, NJ, 08544, USA
| | - Chunting Zhang
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Ryan W Russell
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Sabine Petry
- Department of Molecular Biology, Princeton University, Princeton, NJ, 08544, USA.
| | - Tatyana Polenova
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
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13
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Pibuel MA, Poodts D, Molinari Y, Díaz M, Amoia S, Byrne A, Hajos S, Lompardía S, Franco P. The importance of RHAMM in the normal brain and gliomas: physiological and pathological roles. Br J Cancer 2023; 128:12-20. [PMID: 36207608 PMCID: PMC9814267 DOI: 10.1038/s41416-022-01999-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 09/19/2022] [Accepted: 09/22/2022] [Indexed: 01/27/2023] Open
Abstract
Although the literature about the functions of hyaluronan and the CD44 receptor in the brain and brain tumours is extensive, the role of the receptor for hyaluronan-mediated motility (RHAMM) in neural stem cells and gliomas remain poorly explored. RHAMM is considered a multifunctional receptor which performs various biological functions in several normal tissues and plays a significant role in cancer development and progression. RHAMM was first identified for its ability to bind to hyaluronate, the extracellular matrix component associated with cell motility control. Nevertheless, additional functions of this protein imply the interaction with different partners or cell structures to regulate other biological processes, such as mitotic-spindle assembly, gene expression regulation, cell-cycle control and proliferation. In this review, we summarise the role of RHAMM in normal brain development and the adult brain, focusing on the neural stem and progenitor cells, and discuss the current knowledge on RHAMM involvement in glioblastoma progression, the most aggressive glioma of the central nervous system. Understanding the implications of RHAMM in the brain could be useful to design new therapeutic approaches to improve the prognosis and quality of life of glioblastoma patients.
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Affiliation(s)
- Matías A Pibuel
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica; Departamento de Microbiología, Inmunología y Biotecnología; Instituto de Estudios de la Inmunidad Humoral (IDEHU)-CONICET, Capital Federal (1113), Buenos Aires, Argentina.
| | - Daniela Poodts
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica; Departamento de Microbiología, Inmunología y Biotecnología; Instituto de Estudios de la Inmunidad Humoral (IDEHU)-CONICET, Capital Federal (1113), Buenos Aires, Argentina
| | - Yamila Molinari
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica; Departamento de Química Biológica. Instituto de Química y Fisicoquímica Biológicas (IQUIFIB)-CONICET, Capital Federal (1113), Buenos Aires, Argentina
| | - Mariángeles Díaz
- Instituto de Estudios de la Inmunidad Humoral (IDEHU)- CONICET, Universidad de Buenos Aires, Capital Federal (1113), Buenos Aires, Argentina
| | - Sofía Amoia
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica; Departamento de Microbiología, Inmunología y Biotecnología; Instituto de Estudios de la Inmunidad Humoral (IDEHU)-CONICET, Capital Federal (1113), Buenos Aires, Argentina
| | - Agustín Byrne
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica; Departamento de Química Biológica. Instituto de Química y Fisicoquímica Biológicas (IQUIFIB)-CONICET, Capital Federal (1113), Buenos Aires, Argentina
| | - Silvia Hajos
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica; Departamento de Microbiología, Inmunología y Biotecnología; Instituto de Estudios de la Inmunidad Humoral (IDEHU)-CONICET, Capital Federal (1113), Buenos Aires, Argentina
| | - Silvina Lompardía
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica; Departamento de Microbiología, Inmunología y Biotecnología; Instituto de Estudios de la Inmunidad Humoral (IDEHU)-CONICET, Capital Federal (1113), Buenos Aires, Argentina
| | - Paula Franco
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica; Departamento de Química Biológica. Instituto de Química y Fisicoquímica Biológicas (IQUIFIB)-CONICET, Capital Federal (1113), Buenos Aires, Argentina
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14
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Effects of Ran-GTP/importin β inhibition on the meiotic division of porcine oocytes. Histochem Cell Biol 2022; 158:571-582. [PMID: 35930054 DOI: 10.1007/s00418-022-02134-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/27/2022] [Indexed: 12/13/2022]
Abstract
The Ran-GTP/importin β pathway has been implicated in a diverse array of mitotic functions in somatic mitosis; however, the possible meiotic roles of Ran-GTP/importin β in mammalian oocyte meiosis are still not fully understood. In the present study, importazole (IPZ), a small molecule inhibitor of the interaction between Ran and importin β was used to explore the potential meiotic roles of Ran-GTP/importin β in porcine oocytes undergoing meiosis. After IPZ treatment, the extrusion rate of the first polar body (PB1) was significantly decreased, and a higher proportion of the oocytes were arrested at the germinal vesicle breakdown (GVBD) stage. Moreover, IPZ treatment led to severe defects in metaphase I (MI) spindle assembly and chromosome alignment during the germinal vesicle (GV)-to-MI stage, as well as failure of metaphase II (MII) spindle reassembly and homologous chromosome segregation during the MI-to-MII stage. Notably, IPZ treatment decreased TPX2 expression and abnormal subcellular localization. Furthermore, the expression levels of aurora kinase A (AURKA) and transforming acidic coiled-coil 3 (TACC3) were significantly reduced after IPZ treatment. Collectively, these data indicate that the interaction of Ran-GTP and importin β is essential for proper spindle assembly and successful chromosome segregation during two consecutive meiotic divisions in porcine oocytes, and regulation of this complex might be related to its effect on the TPX2 signaling cascades.
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15
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Timón Pérez K, Scrofani J, Vernos I. NEDD1-S411 phosphorylation plays a critical function in the coordination of microtubule nucleation during mitosis. Biol Open 2022; 11:278477. [PMID: 36318115 PMCID: PMC9836086 DOI: 10.1242/bio.059474] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 10/11/2022] [Indexed: 11/06/2022] Open
Abstract
During mitosis, spindle assembly relies on centrosomal and acentrosomal microtubule nucleation pathways that all require the γ-Tubulin Ring Complex (γ-TuRC) and its adaptor protein NEDD1. The activity of these different pathways needs to be coordinated to ensure bipolar spindle assembly ( Cavazza et al., 2016) but the underlying mechanism is still unclear. Previous studies have identified three sites in NEDD1 (S377, S405 and S411) that when phosphorylated drive MT nucleation at the centrosomes, around the chromosomes and on pre-existing MTs respectively ( Lüders et al., 2006; Pinyol et al., 2013; Sdelci et al., 2012). Here we aimed at getting additional insights into the mechanism that coordinates the different MT nucleation pathways in dividing cells using a collection of HeLa stable inducible cell lines expressing NEDD1 phospho-variants at these three sites and Xenopus egg extracts. Our results provide further support for the essential role of phosphorylation at the three residues. Moreover, we directly demonstrate that S411 phosphorylation is essential for MT branching using TIRF microscopy in Xenopus egg extracts and we show that it plays a crucial role in ensuring the balance between centrosome and chromosome-dependent MT nucleation required for bipolar spindle assembly in mitotic cells.
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Affiliation(s)
- Krystal Timón Pérez
- Quantitative Cell Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona 08003, Spain
| | - Jacopo Scrofani
- Quantitative Cell Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona 08003, Spain,Author for correspondence ()
| | - Isabelle Vernos
- Quantitative Cell Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona 08003, Spain,Universitat Pompeu Fabra (UPF), Barcelona 08003, Spain,ICREA, Pg. Lluis Companys 23, Barcelona 08010, Spain,Author for correspondence ()
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16
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Oh W, Wu TT, Jeong SY, You HJ, Lee JH. CtIP Regulates Mitotic Spindle Assembly by Modulating the TPX2-Aurora A Signaling Axis. Cells 2022; 11:cells11182814. [PMID: 36139389 PMCID: PMC9497199 DOI: 10.3390/cells11182814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 09/07/2022] [Accepted: 09/07/2022] [Indexed: 11/16/2022] Open
Abstract
CtBP-interacting protein (CtIP) plays a critical role in controlling the homologous recombination-mediated DNA double-stranded break (DSB) repair pathway through DNA end resection, and recent studies suggest that it also plays a role in mitosis. However, the mechanism by which CtIP contributes to mitosis regulation remains elusive. Here, we show that depletion of CtIP leads to a delay in anaphase progression resulting in misaligned chromosomes, an aberrant number of centrosomes, and defects in chromosome segregation. Additionally, we demonstrate that CtIP binds and colocalizes with Targeting protein for Xklp2 (TPX2) during mitosis to regulate the recruitment of TPX2 to the spindle poles. Furthermore, depletion of CtIP resulted in both a lower concentration of Aurora A, its downstream target, and very low microtubule intensity at the spindle poles, suggesting an important role for the CtIP-TPX2-Auroa A complex in microtubule dynamics at the centrosomal spindles. Our findings reveal a novel function of CtIP in regulating spindle dynamics through interactions with TPX2 and indicate that CtIP is involved in the proper execution of the mitotic program, where deregulation may lead to chromosomal instability.
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Affiliation(s)
- Wonkyung Oh
- Laboratory of Genomic Instability and Cancer Therapeutics, Cancer Mutation Research Center, School of Medicine, Chosun University, 375 Seosuk-dong, Gwangju 61452, Korea
| | - Ting Ting Wu
- Laboratory of Genomic Instability and Cancer Therapeutics, Cancer Mutation Research Center, School of Medicine, Chosun University, 375 Seosuk-dong, Gwangju 61452, Korea
| | - Seo-Yeon Jeong
- Laboratory of Genomic Instability and Cancer Therapeutics, Cancer Mutation Research Center, School of Medicine, Chosun University, 375 Seosuk-dong, Gwangju 61452, Korea
| | - Ho Jin You
- Laboratory of Genomic Instability and Cancer Therapeutics, Cancer Mutation Research Center, School of Medicine, Chosun University, 375 Seosuk-dong, Gwangju 61452, Korea
- Department of Pharmacology, School of Medicine, Chosun University, 375 Seosuk-dong, Gwangju 61452, Korea
| | - Jung-Hee Lee
- Laboratory of Genomic Instability and Cancer Therapeutics, Cancer Mutation Research Center, School of Medicine, Chosun University, 375 Seosuk-dong, Gwangju 61452, Korea
- Department of Cellular and Molecular Medicine, School of Medicine, Chosun University, 375 Seosuk-dong, Gwangju 61452, Korea
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17
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Sulimenko V, Dráberová E, Dráber P. γ-Tubulin in microtubule nucleation and beyond. Front Cell Dev Biol 2022; 10:880761. [PMID: 36158181 PMCID: PMC9503634 DOI: 10.3389/fcell.2022.880761] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 08/03/2022] [Indexed: 11/13/2022] Open
Abstract
Microtubules composed of αβ-tubulin dimers are dynamic cytoskeletal polymers that play key roles in essential cellular processes such as cell division, organelle positioning, intracellular transport, and cell migration. γ-Tubulin is a highly conserved member of the tubulin family that is required for microtubule nucleation. γ-Tubulin, together with its associated proteins, forms the γ-tubulin ring complex (γ-TuRC), that templates microtubules. Here we review recent advances in the structure of γ-TuRC, its activation, and centrosomal recruitment. This provides new mechanistic insights into the molecular mechanism of microtubule nucleation. Accumulating data suggest that γ-tubulin also has other, less well understood functions. We discuss emerging evidence that γ-tubulin can form oligomers and filaments, has specific nuclear functions, and might be involved in centrosomal cross-talk between microtubules and microfilaments.
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Affiliation(s)
| | | | - Pavel Dráber
- *Correspondence: Vadym Sulimenko, ; Pavel Dráber,
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18
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Modification of BRCA1-associated breast cancer risk by HMMR overexpression. Nat Commun 2022; 13:1895. [PMID: 35393420 PMCID: PMC8989921 DOI: 10.1038/s41467-022-29335-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 03/09/2022] [Indexed: 12/12/2022] Open
Abstract
Breast cancer risk for carriers of BRCA1 pathological variants is modified by genetic factors. Genetic variation in HMMR may contribute to this effect. However, the impact of risk modifiers on cancer biology remains undetermined and the biological basis of increased risk is poorly understood. Here, we depict an interplay of molecular, cellular, and tissue microenvironment alterations that increase BRCA1-associated breast cancer risk. Analysis of genome-wide association results suggests that diverse biological processes, including links to BRCA1-HMMR profiles, influence risk. HMMR overexpression in mouse mammary epithelium increases Brca1-mutant tumorigenesis by modulating the cancer cell phenotype and tumor microenvironment. Elevated HMMR activates AURKA and reduces ARPC2 localization in the mitotic cell cortex, which is correlated with micronucleation and activation of cGAS-STING and non-canonical NF-κB signaling. The initial tumorigenic events are genomic instability, epithelial-to-mesenchymal transition, and tissue infiltration of tumor-associated macrophages. The findings reveal a biological foundation for increased risk of BRCA1-associated breast cancer.
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19
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Verma V, Maresca TJ. A celebration of the 25th anniversary of chromatin-mediated spindle assembly. Mol Biol Cell 2022; 33:rt1. [PMID: 35076260 PMCID: PMC9236140 DOI: 10.1091/mbc.e21-08-0400] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Formation of a bipolar spindle is required for the faithful segregation of chromosomes during cell division. Twenty-five years ago, a transformative insight into how bipolarity is achieved was provided by Rebecca Heald, Eric Karsenti, and colleagues in their landmark publication characterizing a chromatin-mediated spindle assembly pathway in which centrosomes and kinetochores were dispensable. The discovery revealed that bipolar spindle assembly is a self-organizing process where microtubules, which possess an intrinsic polarity, polymerize around chromatin and become sorted by mitotic motors into a bipolar structure. On the 25th anniversary of this seminal paper, we discuss what was known before, what we have learned since, and what may lie ahead in understanding the bipolar spindle.
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Affiliation(s)
- Vikash Verma
- Biology Department, University of Massachusetts, Amherst, Amherst, MA 01003
| | - Thomas J Maresca
- Biology Department, University of Massachusetts, Amherst, Amherst, MA 01003.,Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, Amherst, MA 01003
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20
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Various effects of two types of kinesin-5 inhibitors on mitosis and cell proliferation. Biochem Pharmacol 2021; 193:114789. [PMID: 34582773 DOI: 10.1016/j.bcp.2021.114789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 09/23/2021] [Accepted: 09/23/2021] [Indexed: 11/21/2022]
Abstract
Kinesin-5 has received considerable attention as a new target for mitosis. Various small-molecule compounds targeting kinesin-5 have been developed in the last few decades. However, the differences in the cellular effects of kinesin-5 inhibitors remain poorly understood. Here, we used two different kinesin-5 inhibitors, biphenyl-type PVZB1194 and S-trityl-L-cysteine-type PVEI0021, to examine their effects on molecular events involving kinesin-5. Our biochemical study of kinesin-5 protein-protein interactions showed that PVZB1194-treated kinesin-5 interacted with TPX2 microtubule nucleation factor, Aurora-A kinase, receptor for hyaluronan-mediated motility, and γ-tubulin, as did untreated mitotic kinesin-5. However, PVEI0021 prevented kinesin-5 from binding to these proteins. In mitotic HeLa cells recovered from nocodazole inhibition, kinesin-5 colocalized with these binding proteins, along with microtubules nucleated near kinetochores. By acting on kinesin-5 interactions with chromatin-associated microtubules, PVZB1194, rather than PVEI0021, not only affected the formation of dispersed microtubule clusters but also enhanced the stability of microtubules. In addition, screening for mitotic inhibitors working synergistically with the kinesin-5 inhibitors revealed that paclitaxel synergistically inhibited HeLa cell proliferation only with PVZB1194. In contrast, the Aurora-A inhibitor MLN8237 exerted a synergistic anti-cell proliferation effect when combined with either inhibitor. Together, these results have provided a better understanding of the molecular action of kinesin-5 inhibitors and indicate their usefulness as molecular tools for the study of mitosis and the development of anticancer agents.
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21
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RHAMM Is a Multifunctional Protein That Regulates Cancer Progression. Int J Mol Sci 2021; 22:ijms221910313. [PMID: 34638654 PMCID: PMC8508827 DOI: 10.3390/ijms221910313] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 09/20/2021] [Accepted: 09/21/2021] [Indexed: 01/09/2023] Open
Abstract
The functional complexity of higher organisms is not easily accounted for by the size of their genomes. Rather, complexity appears to be generated by transcriptional, translational, and post-translational mechanisms and tissue organization that produces a context-dependent response of cells to specific stimuli. One property of gene products that likely increases the ability of cells to respond to stimuli with complexity is the multifunctionality of expressed proteins. Receptor for hyaluronan-mediated motility (RHAMM) is an example of a multifunctional protein that controls differential responses of cells in response-to-injury contexts. Here, we trace its evolution into a sensor-transducer of tissue injury signals in higher organisms through the detection of hyaluronan (HA) that accumulates in injured microenvironments. Our goal is to highlight the domain and isoform structures that generate RHAMM's function complexity and model approaches for targeting its key functions to control cancer progression.
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22
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Delimitreva SM, Boneva GV, Chakarova IV, Hadzhinesheva VP, Zhivkova RS, Markova MD, Nikolova VP, Kolarov AI, Mladenov NJ, Bradyanova SL, Tchorbanov AI. Defective oogenesis in mice with pristane-induced model of systemic lupus. J Reprod Immunol 2021; 148:103370. [PMID: 34492566 DOI: 10.1016/j.jri.2021.103370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 07/15/2021] [Accepted: 09/01/2021] [Indexed: 11/15/2022]
Abstract
Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease characterized by generation of autoantibodies and severe damage of various organs. The hormonal changes associated with pregnancy and especially estrogen might lead to damage of reproductive function and ovarian quality. We employed a pristane-induced lupus model of Balb/c mice which resembles human lupus in an attempt to follow oogenesis disruption during the disease progression. The integrity of cytoskeletal and chromatin structures was estimated in oocytes derived by hormonally stimulated ovulation in lupus mice and the results were compared with those from healthy mice. Chromatin, tubulin and actin structures in oocytes were detected by Hoechst 33258, anti-alpha-tubulin antibody and rhodamine-labeled phalloidin, respectively. All available meiotic spindles were analyzed - in immature (metaphase I) and mature oocytes (metaphase II). The total number of mature oocytes obtained from lupus mice was lower compared to healthy controls. The maturation rate was 9.8 % for lupus mice, 12.7 % for 7-month old controls, and 14.3 % for the young control mice (4 weeks old). Another major difference between the studied groups was the higher percentage of defective metaphase I spindles registered in oocytes derived from lupus mice (60 % normal spindles), while for the young and older controls this proportion was 86 % and 81 %, respectively. No such difference was registered for metaphase II spindles. For both metaphase I and metaphase II oocytes, the proportions of normal actin cap and chromosomal condensation were similar between the experimental groups.
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Affiliation(s)
| | - Gabriela V Boneva
- Laboratory of Experimental Immunology, Institute of Microbiology, Bulgarian Academy of Sciences, 1113, Sofia, Bulgaria
| | - Irina V Chakarova
- Department of Biology, Medical University of Sofia, 1431, Sofia, Bulgaria
| | | | - Ralitsa S Zhivkova
- Department of Biology, Medical University of Sofia, 1431, Sofia, Bulgaria
| | - Maya D Markova
- Department of Biology, Medical University of Sofia, 1431, Sofia, Bulgaria
| | - Venera P Nikolova
- Department of Biology, Medical University of Sofia, 1431, Sofia, Bulgaria
| | - Anton I Kolarov
- Department of Biology, Medical University of Sofia, 1431, Sofia, Bulgaria
| | - Nikola J Mladenov
- Department of Biology, Medical University of Sofia, 1431, Sofia, Bulgaria
| | - Silviya L Bradyanova
- Laboratory of Experimental Immunology, Institute of Microbiology, Bulgarian Academy of Sciences, 1113, Sofia, Bulgaria
| | - Andrey I Tchorbanov
- Laboratory of Experimental Immunology, Institute of Microbiology, Bulgarian Academy of Sciences, 1113, Sofia, Bulgaria; National Institute of Immunology, 1517, Sofia, Bulgaria.
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23
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Mesic A, Rogar M, Hudler P, Bilalovic N, Eminovic I, Komel R. Genetic variations in AURORA cell cycle kinases are associated with glioblastoma multiforme. Sci Rep 2021; 11:17444. [PMID: 34465813 PMCID: PMC8408269 DOI: 10.1038/s41598-021-96935-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 08/18/2021] [Indexed: 11/30/2022] Open
Abstract
Glioblastoma multiforme (GBM) is the most frequent type of primary astrocytomas. We examined the association between single nucleotide polymorphisms (SNPs) in Aurora kinase A (AURKA), Aurora kinase B (AURKB), Aurora kinase C (AURKC) and Polo-like kinase 1 (PLK1) mitotic checkpoint genes and GBM risk by qPCR genotyping. In silico analysis was performed to evaluate effects of polymorphic biological sequences on protein binding motifs. Chi-square and Fisher statistics revealed a significant difference in genotypes frequencies between GBM patients and controls for AURKB rs2289590 variant (p = 0.038). Association with decreased GBM risk was demonstrated for AURKB rs2289590 AC genotype (OR = 0.54; 95% CI = 0.33-0.88; p = 0.015). Furthermore, AURKC rs11084490 CG genotype was associated with lower GBM risk (OR = 0.57; 95% CI = 0.34-0.95; p = 0.031). Bioinformatic analysis of rs2289590 polymorphic region identified additional binding site for the Yin-Yang 1 (YY1) transcription factor in the presence of C allele. Our results indicated that rs2289590 in AURKB and rs11084490 in AURKC were associated with a reduced GBM risk. The present study was performed on a less numerous but ethnically homogeneous population. Hence, future investigations in larger and multiethnic groups are needed to strengthen these results.
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Affiliation(s)
- Aner Mesic
- Department of Biology, Faculty of Science, University of Sarajevo, Zmaja od Bosne 33-35, 71000, Sarajevo, Bosnia and Herzegovina
| | - Marija Rogar
- Medical Centre for Molecular Biology, Institute of Biochemistry and Molecular Genetics, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000, Ljubljana, Slovenia
| | - Petra Hudler
- Medical Centre for Molecular Biology, Institute of Biochemistry and Molecular Genetics, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000, Ljubljana, Slovenia.
| | - Nurija Bilalovic
- Clinical Pathology and Cytology, University Clinical Centre Sarajevo, Bolnička 25, 71000, Sarajevo, Bosnia and Herzegovina
| | - Izet Eminovic
- Department of Biology, Faculty of Science, University of Sarajevo, Zmaja od Bosne 33-35, 71000, Sarajevo, Bosnia and Herzegovina
| | - Radovan Komel
- Medical Centre for Molecular Biology, Institute of Biochemistry and Molecular Genetics, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000, Ljubljana, Slovenia
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24
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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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25
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Tovey CA, Tsuji C, Egerton A, Bernard F, Guichet A, de la Roche M, Conduit PT. Autoinhibition of Cnn binding to γ-TuRCs prevents ectopic microtubule nucleation and cell division defects. J Cell Biol 2021; 220:212197. [PMID: 34042945 PMCID: PMC8164090 DOI: 10.1083/jcb.202010020] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 03/25/2021] [Accepted: 05/05/2021] [Indexed: 12/22/2022] Open
Abstract
γ-Tubulin ring complexes (γ-TuRCs) nucleate microtubules. They are recruited to centrosomes in dividing cells via binding to N-terminal CM1 domains within γ-TuRC–tethering proteins, including Drosophila Centrosomin (Cnn). Binding promotes microtubule nucleation and is restricted to centrosomes in dividing cells, but the mechanism regulating binding remains unknown. Here, we identify an extreme N-terminal CM1 autoinhibition (CAI) domain found specifically within the centrosomal isoform of Cnn (Cnn-C) that inhibits γ-TuRC binding. Robust binding occurs after removal of the CAI domain or with the addition of phosphomimetic mutations, suggesting that phosphorylation helps relieve inhibition. We show that regulation of Cnn binding to γ-TuRCs is isoform specific and that misregulation of binding can result in ectopic cytosolic microtubules and major defects during cell division. We also find that human CDK5RAP2 is autoinhibited from binding γ-TuRCs, suggesting conservation across species. Overall, our results shed light on how and why CM1 domain binding to γ-TuRCs is regulated.
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Affiliation(s)
- Corinne A Tovey
- Department of Zoology, University of Cambridge, Cambridge, UK.,Université de Paris, Centre National de la Recherche Scientifique, Institut Jacques Monod, Paris, France
| | - Chisato Tsuji
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Alice Egerton
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Fred Bernard
- Université de Paris, Centre National de la Recherche Scientifique, Institut Jacques Monod, Paris, France
| | - Antoine Guichet
- Université de Paris, Centre National de la Recherche Scientifique, Institut Jacques Monod, Paris, France
| | - Marc de la Roche
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Paul T Conduit
- Department of Zoology, University of Cambridge, Cambridge, UK.,Université de Paris, Centre National de la Recherche Scientifique, Institut Jacques Monod, Paris, France
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26
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Renda F, Khodjakov A. Role of spatial patterns and kinetochore architecture in spindle morphogenesis. Semin Cell Dev Biol 2021; 117:75-85. [PMID: 33836948 PMCID: PMC8762378 DOI: 10.1016/j.semcdb.2021.03.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 03/25/2021] [Accepted: 03/25/2021] [Indexed: 12/30/2022]
Abstract
Mitotic spindle is a self-assembling macromolecular machine responsible for the faithful segregation of chromosomes during cell division. Assembly of the spindle is believed to be governed by the 'Search & Capture' (S&C) principle in which dynamic microtubules explore space in search of kinetochores while the latter capture microtubules and thus connect chromosomes to the spindle. Due to the stochastic nature of the encounters between kinetochores and microtubules, the time required for incorporating all chromosomes into the spindle is profoundly affected by geometric constraints, such as the size and shape of kinetochores as well as their distribution in space at the onset of spindle assembly. In recent years, several molecular mechanisms that control these parameters have been discovered. It is now clear that stochastic S&C takes place in structured space, where components are optimally distributed and oriented to minimize steric hindrances. Nucleation of numerous non-centrosomal microtubules near kinetochores accelerates capture, while changes in the kinetochore architecture at various stages of spindle assembly promote proper connection of sister kinetochores to the opposite spindle poles. Here we discuss how the concerted action of multiple facilitating mechanisms ensure that the spindle assembles rapidly yet with a minimal number of errors.
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Affiliation(s)
- Fioranna Renda
- Biggs Laboratory, Wadsworth Center, New York State Department of Health, Empire State Plaza, Albany, NY 12237, United States.
| | - Alexey Khodjakov
- Biggs Laboratory, Wadsworth Center, New York State Department of Health, Empire State Plaza, Albany, NY 12237, United States; Rensselaer Polytechnic Institute, Troy, NY 12180, United States.
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27
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Jiang Z, Zhang S, Lee YM, Teng X, Yang Q, Toyama Y, Liou YC. Hyaluronan-Mediated Motility Receptor Governs Chromosome Segregation by Regulating Microtubules Sliding Within the Bridging Fiber. Adv Biol (Weinh) 2021; 5:e2000493. [PMID: 33788418 DOI: 10.1002/adbi.202000493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 02/20/2021] [Indexed: 11/06/2022]
Abstract
Accurate segregation of chromosomes during anaphase relies on the central spindle and its regulators. A newly raised concept of the central spindle, the bridging fiber, shows that sliding of antiparallel microtubules (MTs) within the bridging fiber promotes chromosome segregation. However, the regulators of the bridging fiber and its regulatory mechanism on MTs sliding remain largely unknown. In this study, the non-motor microtubule-associated protein, hyaluronan-mediated motility receptor (HMMR), is identified as a novel regulator of the bridging fiber. It then identifies that HMMR regulates MTs sliding within the bridging fiber by cooperating with its binding partner HSET. By utilizing a laser-based cell ablation system and photoactivation approach, the study's results reveal that depletion of HMMR causes an inhibitory effect on MTs sliding within the bridging fiber and disrupts the forced uniformity on the kinetochore-attached microtubules-formed fibers (k-fibers). These are created by suppressing the dynamics of HSET, which functions in transiting the force from sliding of bridging MTs to the k-fiber. This study sheds new light on the novel regulatory mechanism of MTs sliding within the bridging fiber by HMMR and HSET and uncovers the role of HMMR in chromosome segregation during anaphase.
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Affiliation(s)
- Zemin Jiang
- Laboratory of Precision Cancer Medicine, Genome Institute of Singapore (GIS), Agency for Science, Technology and Research (A*STAR), 60 Biopolis Street, #02-01 Genome, Singapore, 138672, Singapore.,Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 117543, Singapore
| | - Shiyu Zhang
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 117543, Singapore
| | - Yew Mun Lee
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 117543, Singapore
| | - Xiang Teng
- Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Qiaoyun Yang
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 117543, Singapore
| | - Yusuke Toyama
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 117543, Singapore.,Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Yih-Cherng Liou
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 117543, Singapore.,Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, 117573, Singapore
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28
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Tsuchiya K, Hayashi H, Nishina M, Okumura M, Sato Y, Kanemaki MT, Goshima G, Kiyomitsu T. Ran-GTP Is Non-essential to Activate NuMA for Mitotic Spindle-Pole Focusing but Dynamically Polarizes HURP Near Chromosomes. Curr Biol 2021; 31:115-127.e3. [DOI: 10.1016/j.cub.2020.09.091] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 08/25/2020] [Accepted: 09/30/2020] [Indexed: 12/27/2022]
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29
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Liu P, Würtz M, Zupa E, Pfeffer S, Schiebel E. Microtubule nucleation: The waltz between γ-tubulin ring complex and associated proteins. Curr Opin Cell Biol 2020; 68:124-131. [PMID: 33190097 DOI: 10.1016/j.ceb.2020.10.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 09/22/2020] [Accepted: 10/08/2020] [Indexed: 12/31/2022]
Abstract
Microtubules are essential cytoskeletal elements assembled from αβ-tubulin dimers. In high eukaryotes, microtubule nucleation, the de novo assembly of a microtubule from its minus end, is initiated by the γ-tubulin ring complex (γ-TuRC). Despite many years of research, the structural and mechanistic principles of the microtubule nucleation machinery remained poorly understood. Only recently, cryoelectron microscopy studies uncovered the molecular organization and potential activation mechanisms of γ-TuRC. In vitro assays further deciphered the spatial and temporal cooperation between γ-TuRC and additional factors, for example, the augmin complex, the phase separation protein TPX2, and the microtubule polymerase XMAP215. These breakthroughs deepen our understanding of microtubule nucleation mechanisms and will link the assembly of individual microtubules to the organization of cellular microtubule networks.
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Affiliation(s)
- Peng Liu
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Im Neuenheimer Feld 282, D-69120, Heidelberg, Germany.
| | - Martin Würtz
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Im Neuenheimer Feld 282, D-69120, Heidelberg, Germany
| | - Erik Zupa
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Im Neuenheimer Feld 282, D-69120, Heidelberg, Germany
| | - Stefan Pfeffer
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Im Neuenheimer Feld 282, D-69120, Heidelberg, Germany
| | - Elmar Schiebel
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), Im Neuenheimer Feld 282, D-69120, Heidelberg, Germany
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30
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Jiang C, Li Z, Wu Z, Liang Y, Jin L, Cao Y, Wan S, Chen Z. Integrated Bioinformatics Analysis of Hub Genes and Pathways Associated with a Compression Model of Spinal Cord Injury in Rats. Med Sci Monit 2020; 26:e927107. [PMID: 33149108 PMCID: PMC7653974 DOI: 10.12659/msm.927107] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Background Spinal cord injury (SCI) is a serious nervous system condition that can cause lifelong disability. The aim of this study was to identify potential molecular mechanisms and therapeutic targets for SCI. Material/Methods We constructed a weighted gene coexpression network and predicted which hub genes are involved in SCI. A compression model of SCI was established in 45 Sprague-Dawley rats, which were divided into 5 groups (n=9 per group): a sham operation group, and 1, 3, 5, and 7 days post-SCI groups. The spinal cord tissue on the injured site was harvested on 1, 3, 5, and 7 days after SCI and 3 days after surgery in the sham operation group. High-throughput sequencing was applied to investigate the expression profile of the mRNA in all samples. Differentially expressed genes were screened and included in weighted gene coexpression network analysis (WGCNA). Co-expressed modules and hub genes were identified by WGCNA. The biological functions of each module were investigated using the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases. Results According to the RNA-seq data, a total of 1965 differentially expressed genes were screened, and WGCNA identified 10 coexpression modules and 5 hub genes. Module function analysis revealed that SCI was associated with immune response, cell division, neuron projection development, and collagen fibril organization. Conclusions Our study revealed dynamic changes in a variety of biological processes following SCI and identified 5 hub genes via WGCNA. These results provide insights into the molecular mechanisms and therapeutic targets of SCI.
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Affiliation(s)
- Chang Jiang
- Department of Orthopaedics, Zhongshan Hospital of Fudan University, Shanghai, China (mainland)
| | - Zheng Li
- Department of Orthopaedics, Zhongshan Hospital of Fudan University, Shanghai, China (mainland)
| | - Zhaoyi Wu
- Department of Orthopaedics, Zhongshan Hospital of Fudan University, Shanghai, China (mainland)
| | - Yun Liang
- Department of Orthopaedics, Zhongshan Hospital of Fudan University, Shanghai, China (mainland)
| | - Lixia Jin
- Department of Orthopaedics, Zhongshan Hospital of Fudan University, Shanghai, China (mainland)
| | - Yuanwu Cao
- Department of Orthopaedics, Zhongshan Hospital of Fudan University, Shanghai, China (mainland)
| | - Shengcheng Wan
- Department of Orthopaedics, Zhongshan Hospital of Fudan University, Shanghai, China (mainland)
| | - Zixian Chen
- Department of Orthopaedics, Zhongshan Hospital of Fudan University, Shanghai, China (mainland)
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31
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Consolati T, Locke J, Roostalu J, Chen ZA, Gannon J, Asthana J, Lim WM, Martino F, Cvetkovic MA, Rappsilber J, Costa A, Surrey T. Microtubule Nucleation Properties of Single Human γTuRCs Explained by Their Cryo-EM Structure. Dev Cell 2020; 53:603-617.e8. [PMID: 32433913 PMCID: PMC7280788 DOI: 10.1016/j.devcel.2020.04.019] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 03/21/2020] [Accepted: 04/27/2020] [Indexed: 12/13/2022]
Abstract
The γ-tubulin ring complex (γTuRC) is the major microtubule nucleator in cells. The mechanism of its regulation is not understood. We purified human γTuRC and measured its nucleation properties in a total internal reflection fluorescence (TIRF) microscopy-based real-time nucleation assay. We find that γTuRC stably caps the minus ends of microtubules that it nucleates stochastically. Nucleation is inefficient compared with microtubule elongation. The 4 Å resolution cryoelectron microscopy (cryo-EM) structure of γTuRC, combined with crosslinking mass spectrometry analysis, reveals an asymmetric conformation with only part of the complex in a "closed" conformation matching the microtubule geometry. Actin in the core of the complex, and MZT2 at the outer perimeter of the closed part of γTuRC appear to stabilize the closed conformation. The opposite side of γTuRC is in an "open," nucleation-incompetent conformation, leading to a structural asymmetry explaining the low nucleation efficiency of purified human γTuRC. Our data suggest possible regulatory mechanisms for microtubule nucleation by γTuRC closure.
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Affiliation(s)
- Tanja Consolati
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology (BIST), Dr Aiguader 88, 08003 Barcelona, Spain
| | - Julia Locke
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | | | - Zhuo Angel Chen
- Bioanalytics, Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany; Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Julian Gannon
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Jayant Asthana
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology (BIST), Dr Aiguader 88, 08003 Barcelona, Spain
| | - Wei Ming Lim
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology (BIST), Dr Aiguader 88, 08003 Barcelona, Spain
| | | | | | - Juri Rappsilber
- Bioanalytics, Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany; Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Alessandro Costa
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.
| | - Thomas Surrey
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology (BIST), Dr Aiguader 88, 08003 Barcelona, Spain; ICREA, Passeig de Lluis Companys 23, 08010 Barcelona, Spain.
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32
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Microtubule Organization in Striated Muscle Cells. Cells 2020; 9:cells9061395. [PMID: 32503326 PMCID: PMC7349303 DOI: 10.3390/cells9061395] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 05/25/2020] [Accepted: 05/28/2020] [Indexed: 12/13/2022] Open
Abstract
Distinctly organized microtubule networks contribute to the function of differentiated cell types such as neurons, epithelial cells, skeletal myotubes, and cardiomyocytes. In striated (i.e., skeletal and cardiac) muscle cells, the nuclear envelope acts as the dominant microtubule-organizing center (MTOC) and the function of the centrosome—the canonical MTOC of mammalian cells—is attenuated, a common feature of differentiated cell types. We summarize the mechanisms known to underlie MTOC formation at the nuclear envelope, discuss the significance of the nuclear envelope MTOC for muscle function and cell cycle progression, and outline potential mechanisms of centrosome attenuation.
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33
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He Z, Mei L, Connell M, Maxwell CA. Hyaluronan Mediated Motility Receptor (HMMR) Encodes an Evolutionarily Conserved Homeostasis, Mitosis, and Meiosis Regulator Rather than a Hyaluronan Receptor. Cells 2020; 9:cells9040819. [PMID: 32231069 PMCID: PMC7226759 DOI: 10.3390/cells9040819] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 03/24/2020] [Accepted: 03/25/2020] [Indexed: 12/21/2022] Open
Abstract
Hyaluronan is an extracellular matrix component that absorbs water in tissues and engages cell surface receptors, like Cluster of Differentiation 44 (CD44), to promote cellular growth and movement. Consequently, CD44 demarks stem cells in normal tissues and tumor-initiating cells isolated from neoplastic tissues. Hyaluronan mediated motility receptor (HMMR, also known as RHAMM) is another one of few defined hyaluronan receptors. HMMR is also associated with neoplastic processes and its role in cancer progression is often attributed to hyaluronan-mediated signaling. But, HMMR is an intracellular, microtubule-associated, spindle assembly factor that localizes protein complexes to augment the activities of mitotic kinases, like polo-like kinase 1 and Aurora kinase A, and control dynein and kinesin motor activities. Expression of HMMR is elevated in cells prior to and during mitosis and tissues with detectable HMMR expression tend to be highly proliferative, including neoplastic tissues. Moreover, HMMR is a breast cancer susceptibility gene product. Here, we briefly review the associations between HMMR and tumorigenesis as well as the structure and evolution of HMMR, which identifies Hmmr-like gene products in several insect species that do not produce hyaluronan. This review supports the designation of HMMR as a homeostasis, mitosis, and meiosis regulator, and clarifies how its dysfunction may promote the tumorigenic process and cancer progression.
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Affiliation(s)
- Zhengcheng He
- Department of Pediatrics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada; (Z.H.); (L.M.); (M.C.)
| | - Lin Mei
- Department of Pediatrics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada; (Z.H.); (L.M.); (M.C.)
| | - Marisa Connell
- Department of Pediatrics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada; (Z.H.); (L.M.); (M.C.)
| | - Christopher A. Maxwell
- Department of Pediatrics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada; (Z.H.); (L.M.); (M.C.)
- Michael Cuccione Childhood Cancer Research Program, BC Children’s Hospital, Vancouver, BC V5Z 4H4, Canada
- Correspondence: ; Tel.: +1-6048752000 (ext. 4691)
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34
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Fulcher LJ, Sapkota GP. Mitotic kinase anchoring proteins: the navigators of cell division. Cell Cycle 2020; 19:505-524. [PMID: 32048898 PMCID: PMC7100989 DOI: 10.1080/15384101.2020.1728014] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 01/14/2020] [Accepted: 02/06/2020] [Indexed: 02/07/2023] Open
Abstract
The coordinated activities of many protein kinases, acting on multiple protein substrates, ensures the error-free progression through mitosis of eukaryotic cells. Enormous research effort has thus been devoted to studying the roles and regulation of these mitotic kinases, and to the identification of their physiological substrates. Central for the timely deployment of specific protein kinases to their appropriate substrates during the cell division cycle are the many anchoring proteins, which serve critical regulatory roles. Through direct association, anchoring proteins are capable of modulating the catalytic activity and/or sub-cellular distribution of the mitotic kinases they associate with. The key roles of some anchoring proteins in cell division are well-established, whilst others are still being unearthed. Here, we review the current knowledge on anchoring proteins for some mitotic kinases, and highlight how targeting anchoring proteins for inhibition, instead of the mitotic kinases themselves, could be advantageous for disrupting the cell division cycle.
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Affiliation(s)
- Luke J Fulcher
- Medical Research Council Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, Scotland, UK
| | - Gopal P Sapkota
- Medical Research Council Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, Scotland, UK
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35
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King MR, Petry S. Phase separation of TPX2 enhances and spatially coordinates microtubule nucleation. Nat Commun 2020; 11:270. [PMID: 31937751 PMCID: PMC6959270 DOI: 10.1038/s41467-019-14087-0] [Citation(s) in RCA: 143] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 12/10/2019] [Indexed: 12/14/2022] Open
Abstract
Phase separation of substrates and effectors is proposed to enhance biological reaction rates and efficiency. Targeting protein for Xklp2 (TPX2) is an effector of branching microtubule nucleation in spindles and functions with the substrate tubulin by an unknown mechanism. Here we show that TPX2 phase separates into a co-condensate with tubulin, which mediates microtubule nucleation in vitro and in isolated cytosol. TPX2-tubulin co-condensation preferentially occurs on pre-existing microtubules, the site of branching microtubule nucleation, at the endogenous and physiologically relevant concentration of TPX2. Truncation and chimera versions of TPX2 suggest that TPX2-tubulin co-condensation enhances the efficiency of TPX2-mediated branching microtubule nucleation. Finally, the known inhibitor of TPX2, the importin-α/β heterodimer, regulates TPX2 condensation in vitro and, consequently, branching microtubule nucleation activity in isolated cytosol. Our study demonstrates how regulated phase separation can simultaneously enhance reaction efficiency and spatially coordinate microtubule nucleation, which may facilitate rapid and accurate spindle formation.
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Affiliation(s)
- Matthew R King
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, 08544, USA
- Department of Biomedical Engineering, Washington University, Brauer Hall, One Brookings Drive, Saint Louis, Missouri, 63130, USA
| | - Sabine Petry
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, 08544, USA.
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36
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Liu P, Zupa E, Neuner A, Böhler A, Loerke J, Flemming D, Ruppert T, Rudack T, Peter C, Spahn C, Gruss OJ, Pfeffer S, Schiebel E. Insights into the assembly and activation of the microtubule nucleator γ-TuRC. Nature 2019; 578:467-471. [DOI: 10.1038/s41586-019-1896-6] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 12/10/2019] [Indexed: 02/06/2023]
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Verma V, Mogilner A, Maresca TJ. Classical and Emerging Regulatory Mechanisms of Cytokinesis in Animal Cells. BIOLOGY 2019; 8:biology8030055. [PMID: 31357447 PMCID: PMC6784142 DOI: 10.3390/biology8030055] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 07/05/2019] [Accepted: 07/23/2019] [Indexed: 12/12/2022]
Abstract
The primary goal of cytokinesis is to produce two daughter cells, each having a full set of chromosomes. To achieve this, cells assemble a dynamic structure between segregated sister chromatids called the contractile ring, which is made up of filamentous actin, myosin-II, and other regulatory proteins. Constriction of the actomyosin ring generates a cleavage furrow that divides the cytoplasm to produce two daughter cells. Decades of research have identified key regulators and underlying molecular mechanisms; however, many fundamental questions remain unanswered and are still being actively investigated. This review summarizes the key findings, computational modeling, and recent advances in understanding of the molecular mechanisms that control the formation of the cleavage furrow and cytokinesis.
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Affiliation(s)
- Vikash Verma
- Biology Department, University of Massachusetts, Amherst, MA 01003, USA.
| | - Alex Mogilner
- Courant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA
- Department of Biology, New York University, New York, NY 10012, USA
| | - Thomas J Maresca
- Biology Department, University of Massachusetts, Amherst, MA 01003, USA
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, MA 01003, USA
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Joukov V, De Nicolo A. The Centrosome and the Primary Cilium: The Yin and Yang of a Hybrid Organelle. Cells 2019; 8:E701. [PMID: 31295970 PMCID: PMC6678760 DOI: 10.3390/cells8070701] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 07/04/2019] [Accepted: 07/06/2019] [Indexed: 12/27/2022] Open
Abstract
Centrosomes and primary cilia are usually considered as distinct organelles, although both are assembled with the same evolutionary conserved, microtubule-based templates, the centrioles. Centrosomes serve as major microtubule- and actin cytoskeleton-organizing centers and are involved in a variety of intracellular processes, whereas primary cilia receive and transduce environmental signals to elicit cellular and organismal responses. Understanding the functional relationship between centrosomes and primary cilia is important because defects in both structures have been implicated in various diseases, including cancer. Here, we discuss evidence that the animal centrosome evolved, with the transition to complex multicellularity, as a hybrid organelle comprised of the two distinct, but intertwined, structural-functional modules: the centriole/primary cilium module and the pericentriolar material/centrosome module. The evolution of the former module may have been caused by the expanding cellular diversification and intercommunication, whereas that of the latter module may have been driven by the increasing complexity of mitosis and the requirement for maintaining cell polarity, individuation, and adhesion. Through its unique ability to serve both as a plasma membrane-associated primary cilium organizer and a juxtanuclear microtubule-organizing center, the animal centrosome has become an ideal integrator of extracellular and intracellular signals with the cytoskeleton and a switch between the non-cell autonomous and the cell-autonomous signaling modes. In light of this hypothesis, we discuss centrosome dynamics during cell proliferation, migration, and differentiation and propose a model of centrosome-driven microtubule assembly in mitotic and interphase cells. In addition, we outline the evolutionary benefits of the animal centrosome and highlight the hierarchy and modularity of the centrosome biogenesis networks.
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Affiliation(s)
- Vladimir Joukov
- N.N. Petrov National Medical Research Center of Oncology, 197758 Saint-Petersburg, Russia.
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David AF, Roudot P, Legant WR, Betzig E, Danuser G, Gerlich DW. Augmin accumulation on long-lived microtubules drives amplification and kinetochore-directed growth. J Cell Biol 2019; 218:2150-2168. [PMID: 31113824 PMCID: PMC6605806 DOI: 10.1083/jcb.201805044] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 12/19/2018] [Accepted: 04/30/2019] [Indexed: 12/31/2022] Open
Abstract
Vertebrate cells assemble mitotic spindles through multiple pathways. It is shown that Augmin-dependent, noncentrosomal nucleation generates the vast majority of microtubules in metaphase spindles. This results in a strong directional bias of microtubule growth toward individual kinetochores. Dividing cells reorganize their microtubule cytoskeleton into a bipolar spindle, which moves one set of sister chromatids to each nascent daughter cell. Early spindle assembly models postulated that spindle pole–derived microtubules search the cytoplasmic space until they randomly encounter a kinetochore to form a stable attachment. More recent work uncovered several additional, centrosome-independent microtubule generation pathways, but the contributions of each pathway to spindle assembly have remained unclear. Here, we combined live microscopy and mathematical modeling to show that most microtubules nucleate at noncentrosomal regions in dividing human cells. Using a live-cell probe that selectively labels aged microtubule lattices, we demonstrate that the distribution of growing microtubule plus ends can be almost entirely explained by Augmin-dependent amplification of long-lived microtubule lattices. By ultrafast 3D lattice light-sheet microscopy, we observed that this mechanism results in a strong directional bias of microtubule growth toward individual kinetochores. Our systematic quantification of spindle dynamics reveals highly coordinated microtubule growth during kinetochore fiber assembly.
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Affiliation(s)
- Ana F David
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna BioCenter, Vienna, Austria
| | - Philippe Roudot
- Department of Cell Biology and Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Wesley R Legant
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Eric Betzig
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Gaudenz Danuser
- Department of Cell Biology and Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Daniel W Gerlich
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna BioCenter, Vienna, Austria
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40
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Moura M, Conde C. Phosphatases in Mitosis: Roles and Regulation. Biomolecules 2019; 9:E55. [PMID: 30736436 PMCID: PMC6406801 DOI: 10.3390/biom9020055] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 01/31/2019] [Accepted: 02/01/2019] [Indexed: 02/07/2023] Open
Abstract
Mitosis requires extensive rearrangement of cellular architecture and of subcellular structures so that replicated chromosomes can bind correctly to spindle microtubules and segregate towards opposite poles. This process originates two new daughter nuclei with equal genetic content and relies on highly-dynamic and tightly regulated phosphorylation of numerous cell cycle proteins. A burst in protein phosphorylation orchestrated by several conserved kinases occurs as cells go into and progress through mitosis. The opposing dephosphorylation events are catalyzed by a small set of protein phosphatases, whose importance for the accuracy of mitosis is becoming increasingly appreciated. This review will focus on the established and emerging roles of mitotic phosphatases, describe their structural and biochemical properties, and discuss recent advances in understanding the regulation of phosphatase activity and function.
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Affiliation(s)
- Margarida Moura
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
- i3S-Instituto de Investigação e Inovação em Saúde da Universidade do Porto, 4200-135, Porto, Portugal.
- Programa Doutoral em Biologia Molecular e Celular (MCbiology), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, 4050-313 Porto, Portugal.
| | - Carlos Conde
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
- i3S-Instituto de Investigação e Inovação em Saúde da Universidade do Porto, 4200-135, Porto, Portugal.
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41
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Courthéoux T, Reboutier D, Vazeille T, Cremet JY, Benaud C, Vernos I, Prigent C. Microtubule nucleation during central spindle assembly requires NEDD1 phosphorylation on Serine 405 by Aurora A. J Cell Sci 2019; 132:jcs.231118. [DOI: 10.1242/jcs.231118] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 04/16/2019] [Indexed: 12/12/2022] Open
Abstract
During mitosis, the cell sequentially constructs two microtubule-based spindles to ensure faithful segregation of chromosomes. A bipolar spindle first pulls apart the sister chromatids, then a central spindle further separates them away. Although the assembly of the first spindle is well described, the assembly of the second remains poorly understood. We report here that the inhibition of Aurora A leads to an absence of the central spindle due to a lack of nucleation of microtubules in the midzone. In the absence of Aurora A, the HURP and NEDD1 proteins that are involved in nucleation of microtubules fail to concentrate in the midzone. HURP is an effector of RanGTP and NEDD1 serves as an anchor for the γTURC. Interestingly, Aurora A already phosphorylates them during assembly of the bipolar spindle. We show here that the expression of a NEDD1 isoform mimicking Aurora A phosphorylation is sufficient to restore microtubule nucleation in the midzone in a context of Aurora A inhibition. These results reveal a new control mechanism of nucleation of microtubules by Aurora A during assembly of the central spindle.
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Affiliation(s)
- Thibault Courthéoux
- Univ. Rennes, CNRS, Institut de Génétique et de Développement de Rennes (IGDR), UMR6290, Equipe labellisée Ligue 2014, F35000 Rennes, France
| | - David Reboutier
- Univ. Rennes, CNRS, Institut de Génétique et de Développement de Rennes (IGDR), UMR6290, Equipe labellisée Ligue 2014, F35000 Rennes, France
| | - Thibaut Vazeille
- Univ. Rennes, CNRS, Institut de Génétique et de Développement de Rennes (IGDR), UMR6290, Equipe labellisée Ligue 2014, F35000 Rennes, France
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Jean-Yves Cremet
- Univ. Rennes, CNRS, Institut de Génétique et de Développement de Rennes (IGDR), UMR6290, Equipe labellisée Ligue 2014, F35000 Rennes, France
| | - Christelle Benaud
- Univ. Rennes, CNRS, Institut de Génétique et de Développement de Rennes (IGDR), UMR6290, Equipe labellisée Ligue 2014, F35000 Rennes, France
| | - Isabelle Vernos
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
- ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
| | - Claude Prigent
- Univ. Rennes, CNRS, Institut de Génétique et de Développement de Rennes (IGDR), UMR6290, Equipe labellisée Ligue 2014, F35000 Rennes, France
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Abstract
Neurons are polarized cells with long branched axons and dendrites. Microtubule generation and organization machineries are crucial to grow and pattern these complex cellular extensions. Microtubule organizing centers (MTOCs) concentrate the molecular machinery for templating microtubules, stabilizing the nascent polymer, and organizing the resultant microtubules into higher-order structures. MTOC formation and function are well described at the centrosome, in the spindle, and at interphase Golgi; we review these studies and then describe recent results about how the machineries acting at these classic MTOCs are repurposed in the postmitotic neuron for axon and dendrite differentiation. We further discuss a constant tug-of-war interplay between different MTOC activities in the cell and how this process can be used as a substrate for transcription factor-mediated diversification of neuron types.
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Affiliation(s)
- Jason Y Tann
- Laboratory for Neurodiversity, RIKEN Centre for Brain Science, Saitama, Japan
| | - Adrian W Moore
- Laboratory for Neurodiversity, RIKEN Centre for Brain Science, Saitama, Japan.
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43
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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: 79] [Impact Index Per Article: 11.3] [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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44
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Abstract
Mitosis is controlled by reversible protein phosphorylation involving specific kinases and phosphatases. A handful of major mitotic protein kinases, such as the cyclin B-CDK1 complex, the Aurora kinases, and Polo-like kinase 1 (PLK1), cooperatively regulate distinct mitotic processes. Research has identified proteins and mechanisms that integrate these kinases into signaling cascades that guide essential mitotic events. These findings have important implications for our understanding of the mechanisms of mitotic regulation and may advance the development of novel antimitotic drugs. We review collected evidence that in vertebrates, the Aurora kinases serve as catalytic subunits of distinct complexes formed with the four scaffold proteins Bora, CEP192, INCENP, and TPX2, which we deem "core" Aurora cofactors. These complexes and the Aurora-PLK1 cascades organized by Bora, CEP192, and INCENP control crucial aspects of mitosis and all pathways of spindle assembly. We compare the mechanisms of Aurora activation in relation to the different spindle assembly pathways and draw a functional analogy between the CEP192 complex and the chromosomal passenger complex that may reflect the coevolution of centrosomes, kinetochores, and the actomyosin cleavage apparatus. We also analyze the roles and mechanisms of Aurora-PLK1 signaling in the cell and centrosome cycles and in the DNA damage response.
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Affiliation(s)
- Vladimir Joukov
- N.N. Petrov National Medical Research Center of Oncology, Saint-Petersburg 197758, Russian Federation.
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45
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Animal Female Meiosis: The Challenges of Eliminating Centrosomes. Cells 2018; 7:cells7070073. [PMID: 29996518 PMCID: PMC6071224 DOI: 10.3390/cells7070073] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 07/03/2018] [Accepted: 07/03/2018] [Indexed: 01/02/2023] Open
Abstract
Sexual reproduction requires the generation of gametes, which are highly specialised for fertilisation. Female reproductive cells, oocytes, grow up to large sizes when they accumulate energy stocks and store proteins as well as mRNAs to enable rapid cell divisions after fertilisation. At the same time, metazoan oocytes eliminate their centrosomes, i.e., major microtubule-organizing centres (MTOCs), during or right after the long growth phases. Centrosome elimination poses two key questions: first, how can the centrosome be re-established after fertilisation? In general, metazoan oocytes exploit sperm components, i.e., the basal body of the sperm flagellum, as a platform to reinitiate centrosome production. Second, how do most metazoan oocytes manage to build up meiotic spindles without centrosomes? Oocytes have evolved mechanisms to assemble bipolar spindles solely around their chromosomes without the guidance of pre-formed MTOCs. Female animal meiosis involves microtubule nucleation and organisation into bipolar microtubule arrays in regulated self-assembly under the control of the Ran system and nuclear transport receptors. This review summarises our current understanding of the molecular mechanism underlying self-assembly of meiotic spindles, its spatio-temporal regulation, and the key players governing this process in animal oocytes.
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46
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Kitaoka M, Heald R, Gibeaux R. Spindle assembly in egg extracts of the Marsabit clawed frog, Xenopus borealis. Cytoskeleton (Hoboken) 2018; 75:244-257. [PMID: 29573195 DOI: 10.1002/cm.21444] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 03/16/2018] [Accepted: 03/19/2018] [Indexed: 11/05/2022]
Abstract
Egg extracts of the African clawed frog Xenopus laevis have provided a cell-free system instrumental in elucidating events of the cell cycle, including mechanisms of spindle assembly. Comparison with extracts from the diploid Western clawed frog, Xenopus tropicalis, which is smaller at the organism, cellular and subcellular levels, has enabled the identification of spindle size scaling factors. We set out to characterize the Marsabit clawed frog, Xenopus borealis, which is intermediate in size between the two species, but more recently diverged in evolution from X. laevis than X. tropicalis. X. borealis eggs were slightly smaller than those of X. laevis, and slightly smaller spindles were assembled in egg extracts. Interestingly, microtubule distribution across the length of the X. borealis spindles differed from both X. laevis and X. tropicalis. Extract mixing experiments revealed common scaling phenomena among Xenopus species, while characterization of spindle factors katanin, TPX2, and Ran indicate that X. borealis spindles possess both X. laevis and X. tropicalis features. Thus, X. borealis egg extract provides a third in vitro system to investigate interspecies scaling and spindle morphometric variation.
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Affiliation(s)
- Maiko Kitaoka
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720
| | - Rebecca Heald
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720
| | - Romain Gibeaux
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720
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47
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Chen H, Connell M, Mei L, Reid GSD, Maxwell CA. The nonmotor adaptor HMMR dampens Eg5-mediated forces to preserve the kinetics and integrity of chromosome segregation. Mol Biol Cell 2018; 29:786-796. [PMID: 29386294 PMCID: PMC5905292 DOI: 10.1091/mbc.e17-08-0531] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The nonmotor adaptor protein HMMR maintains the kinetics and integrity of chromosome segregation by promoting TPX2-Eg5 complexes that dampen Eg5-mediated forces and support K-fiber stability, kinetochore–microtubule attachments, and inter-kinetochore tension. HMMR is needed to prevent the generation of aneuploid progeny cells. Mitotic spindle assembly and organization require forces generated by motor proteins. The activity of these motors is regulated by nonmotor adaptor proteins. However, there are limited studies reporting the functional importance of adaptors on the balance of motor forces and the promotion of faithful and timely cell division. Here we show that genomic deletion or small interfering RNA silencing of the nonmotor adaptor Hmmr/HMMR disturbs spindle microtubule organization and bipolar chromosome–kinetochore attachments with a consequent elevated occurrence of aneuploidy. Rescue experiments show a conserved motif in HMMR is required to generate interkinetochore tension and promote anaphase entry. This motif bears high homology with the kinesin Kif15 and is known to interact with TPX2, a spindle assembly factor. We find that HMMR is required to dampen kinesin Eg5-mediated forces through localizing TPX2 and promoting the formation of inhibitory TPX2-Eg5 complexes. In HMMR-silenced cells, K-fiber stability is reduced while the frequency of unattached chromosomes and the time needed for chromosome segregation are both increased. These defects can be alleviated in HMMR-silenced cells with chemical inhibition of Eg5 but not through the silencing of Kif15. Together, our findings indicate that HMMR balances Eg5-mediated forces to preserve the kinetics and integrity of chromosome segregation.
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Affiliation(s)
- Helen Chen
- Department of Pediatrics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | - Marisa Connell
- Department of Pediatrics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | - Lin Mei
- Department of Pediatrics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada
| | - Gregor S D Reid
- Department of Pediatrics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada.,Michael Cuccione Childhood Cancer Research Program, BC Children's Hospital, Vancouver, BC V5Z 4H4, Canada
| | - Christopher A Maxwell
- Department of Pediatrics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada.,Michael Cuccione Childhood Cancer Research Program, BC Children's Hospital, Vancouver, BC V5Z 4H4, Canada
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48
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Coming into Focus: Mechanisms of Microtubule Minus-End Organization. Trends Cell Biol 2018; 28:574-588. [PMID: 29571882 DOI: 10.1016/j.tcb.2018.02.011] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 02/17/2018] [Accepted: 02/27/2018] [Indexed: 11/22/2022]
Abstract
Microtubule organization has a crucial role in regulating cell architecture. The geometry of microtubule arrays strongly depends on the distribution of sites responsible for microtubule nucleation and minus-end attachment. In cycling animal cells, the centrosome often represents a dominant microtubule-organizing center (MTOC). However, even in cells with a radial microtubule system, many microtubules are not anchored at the centrosome, but are instead linked to the Golgi apparatus or other structures. Non-centrosomal microtubules predominate in many types of differentiated cell and in mitotic spindles. In this review, we discuss recent advances in understanding how the organization of centrosomal and non-centrosomal microtubule networks is controlled by proteins involved in microtubule nucleation and specific factors that recognize free microtubule minus ends and regulate their localization and dynamics.
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49
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Mchedlishvili N, Matthews HK, Corrigan A, Baum B. Two-step interphase microtubule disassembly aids spindle morphogenesis. BMC Biol 2018; 16:14. [PMID: 29361957 PMCID: PMC5778756 DOI: 10.1186/s12915-017-0478-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 12/22/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Entry into mitosis triggers profound changes in cell shape and cytoskeletal organisation. Here, by studying microtubule remodelling in human flat mitotic cells, we identify a two-step process of interphase microtubule disassembly. RESULTS First, a microtubule-stabilising protein, Ensconsin/MAP7, is inactivated in prophase as a consequence of its phosphorylation downstream of Cdk1/cyclin B. This leads to a reduction in interphase microtubule stability that may help to fuel the growth of centrosomally nucleated microtubules. The peripheral interphase microtubules that remain are then rapidly lost as the concentration of tubulin heterodimers falls following dissolution of the nuclear compartment boundary. Finally, we show that a failure to destabilise microtubules in prophase leads to the formation of microtubule clumps, which interfere with spindle assembly. CONCLUSIONS This analysis highlights the importance of the step-wise remodelling of the microtubule cytoskeleton and the significance of permeabilisation of the nuclear envelope in coordinating the changes in cellular organisation and biochemistry that accompany mitotic entry.
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Affiliation(s)
- Nunu Mchedlishvili
- MRC Laboratory of Molecular Cell Biology and the IPLS, University College London, Gower Street, London, WC1E 6BT, UK
| | - Helen K Matthews
- MRC Laboratory of Molecular Cell Biology and the IPLS, University College London, Gower Street, London, WC1E 6BT, UK
| | - Adam Corrigan
- MRC Laboratory of Molecular Cell Biology and the IPLS, University College London, Gower Street, London, WC1E 6BT, UK
| | - Buzz Baum
- MRC Laboratory of Molecular Cell Biology and the IPLS, University College London, Gower Street, London, WC1E 6BT, UK.
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50
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Zhang R, Roostalu J, Surrey T, Nogales E. Structural insight into TPX2-stimulated microtubule assembly. eLife 2017; 6. [PMID: 29120325 PMCID: PMC5679754 DOI: 10.7554/elife.30959] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 10/29/2017] [Indexed: 11/13/2022] Open
Abstract
During mitosis and meiosis, microtubule (MT) assembly is locally upregulated by the chromatin-dependent Ran-GTP pathway. One of its key targets is the MT-associated spindle assembly factor TPX2. The molecular mechanism of how TPX2 stimulates MT assembly remains unknown because structural information about the interaction of TPX2 with MTs is lacking. Here, we determine the cryo-electron microscopy structure of a central region of TPX2 bound to the MT surface. TPX2 uses two flexibly linked elements ('ridge' and 'wedge') in a novel interaction mode to simultaneously bind across longitudinal and lateral tubulin interfaces. These MT-interacting elements overlap with the binding site of importins on TPX2. Fluorescence microscopy-based in vitro reconstitution assays reveal that this interaction mode is critical for MT binding and facilitates MT nucleation. Together, our results suggest a molecular mechanism of how the Ran-GTP gradient can regulate TPX2-dependent MT formation.
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Affiliation(s)
- Rui Zhang
- Molecular Biophysics and Integrative Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, United States
| | | | | | - Eva Nogales
- Molecular Biophysics and Integrative Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, United States.,Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
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