1
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Woodard TK, Rioux DJ, Prosser DC. Actin- and microtubule-based motors contribute to clathrin-independent endocytosis in yeast. Mol Biol Cell 2023; 34:ar117. [PMID: 37647159 PMCID: PMC10846617 DOI: 10.1091/mbc.e23-05-0164] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 08/14/2023] [Accepted: 08/22/2023] [Indexed: 09/01/2023] Open
Abstract
Most eukaryotic cells utilize clathrin-mediated endocytosis as well as multiple clathrin-independent pathways to internalize proteins and membranes. Although clathrin-mediated endocytosis has been studied extensively and many machinery proteins have been identified, clathrin-independent pathways remain poorly characterized by comparison. We previously identified the first known yeast clathrin-independent endocytic pathway, which relies on the actin-modulating GTPase Rho1, the formin Bni1 and unbranched actin filaments, but does not require the clathrin coat or core clathrin machinery proteins. In this study, we sought to better understand clathrin-independent endocytosis in yeast by exploring the role of myosins as actin-based motors, because actin is required for endocytosis in yeast. We find that Myo2, which transports secretory vesicles, organelles and microtubules along actin cables to sites of polarized growth, participates in clathrin-independent endocytosis. Unexpectedly, the ability of Myo2 to transport microtubule plus ends to the cell cortex appears to be required for its role in clathrin-independent endocytosis. In addition, dynein, dynactin, and proteins involved in cortical microtubule capture are also required. Thus, our results suggest that interplay between actin and microtubules contributes to clathrin-independent internalization in yeast.
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Affiliation(s)
| | - Daniel J. Rioux
- Department of Biology, Virginia Commonwealth University, Richmond, VA 23284
- Life Sciences, Virginia Commonwealth University, Richmond, VA 23284
| | - Derek C. Prosser
- Department of Biology, Virginia Commonwealth University, Richmond, VA 23284
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2
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Yang S, Cai M, Huang J, Zhang S, Mo X, Jiang K, Cui H, Yuan J. EB1 decoration of microtubule lattice facilitates spindle-kinetochore lateral attachment in Plasmodium male gametogenesis. Nat Commun 2023; 14:2864. [PMID: 37208365 DOI: 10.1038/s41467-023-38516-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 05/04/2023] [Indexed: 05/21/2023] Open
Abstract
Faithful chromosome segregation of 8 duplicated haploid genomes into 8 daughter gametes is essential for male gametogenesis and mosquito transmission of Plasmodium. Plasmodium undergoes endomitosis in this multinucleated cell division, which is highly reliant on proper spindle-kinetochore attachment. However, the mechanisms underlying the spindle-kinetochore attachment remain elusive. End-binding proteins (EBs) are conserved microtubule (MT) plus-end binding proteins and play an important role in regulating MT plus-end dynamics. Here, we report that the Plasmodium EB1 is an orthologue distinct from the canonical eukaryotic EB1. Both in vitro and in vivo assays reveal that the Plasmodium EB1 losses MT plus-end tracking but possesses MT-lattice affinity. This MT-binding feature of Plasmodium EB1 is contributed by both CH domain and linker region. EB1-deficient parasites produce male gametocytes that develop to the anucleated male gametes, leading to defective mosquito transmission. EB1 is localized at the nucleoplasm of male gametocytes. During the gametogenesis, EB1 decorates the full-length of spindle MTs and regulates spindle structure. The kinetochores attach to spindle MTs laterally throughout endomitosis and this attachment is EB1-dependent. Consequently, impaired spindle-kinetochore attachment is observed in EB1-deficient parasites. These results indicate that a parasite-specific EB1 with MT-lattice binding affinity fulfills the spindle-kinetochore lateral attachment in male gametogenesis.
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Affiliation(s)
- Shuzhen Yang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China
| | - Mengya Cai
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China
| | - Junjie Huang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology and Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Medical Research Institute, Wuhan University, Wuhan, China
| | - Shengnan Zhang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China
| | - Xiaoli Mo
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China
| | - Kai Jiang
- The State Key Laboratory Breeding Base of Basic Science of Stomatology and Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of Stomatology, Medical Research Institute, Wuhan University, Wuhan, China.
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China.
| | - Huiting Cui
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China.
| | - Jing Yuan
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China.
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3
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The N-Terminal Domain of Bfa1 Coordinates Mitotic Exit Independent of GAP Activity in Saccharomyces cerevisiae. Cells 2022; 11:cells11142179. [PMID: 35883622 PMCID: PMC9316867 DOI: 10.3390/cells11142179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 07/06/2022] [Accepted: 07/07/2022] [Indexed: 12/10/2022] Open
Abstract
The spindle position checkpoint (SPOC) of budding yeast delays mitotic exit in response to misaligned spindles to ensure cell survival and the maintenance of genomic stability. The GTPase-activating protein (GAP) complex Bfa1–Bub2, a key SPOC component, inhibits the GTPase Tem1 to induce mitotic arrest in response to DNA and spindle damage, as well as spindle misorientation. However, previous results strongly suggest that Bfa1 exerts a GAP-independent function in blocking mitotic exit in response to misaligned spindles. Thus, the molecular mechanism by which Bfa1 controls mitotic exit in response to misaligned spindles remains unclear. Here, we observed that overexpression of the N-terminal domain of Bfa1 (Bfa1-D16), which lacks GAP activity and cannot localize to the spindle pole body (SPB), induced cell cycle arrest along with hyper-elongation of astral microtubules (aMTs) as Bfa1 overexpression in Δbub2. We found that Δbub2 cells overexpressing Bfa1 or Bfa1-D16 inhibited activation of Mob1, which is responsible for mitotic exit. In anaphase-arrested cells, Bfa1-D16 overexpression inhibited Tem1 binding to the SPB as well as Bfa1 overexpression. Additionally, endogenous levels of Bfa1-D16 showed minor SPOC activity that was not regulated by Kin4. These results suggested that Bfa1-D16 may block mitotic exit through inhibiting Tem1 activity outside of SPBs. Alternatively, Bfa1-D16 dispersed out of SPBs may block Tem1 binding to SPBs by physically interacting with Tem1 as previously reported. Moreover, we observed hyper-elongated aMTs in tem1-3, cdc15-2, and dbf2-2 mutants that induce anaphase arrest and cannot undergo mitotic exit at restrictive temperatures, suggesting that aMT dynamics are closely related to the regulation of mitotic exit. Altogether, these observations suggest that Bfa1 can control the SPOC independent of its GAP activity and SPB localization.
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4
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Nsamba ET, Bera A, Costanzo M, Boone C, Gupta ML. Tubulin isotypes optimize distinct spindle positioning mechanisms during yeast mitosis. J Cell Biol 2021; 220:212745. [PMID: 34739032 PMCID: PMC8576917 DOI: 10.1083/jcb.202010155] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 09/06/2021] [Accepted: 10/12/2021] [Indexed: 01/13/2023] Open
Abstract
Microtubules are dynamic cytoskeleton filaments that are essential for a wide range of cellular processes. They are polymerized from tubulin, a heterodimer of α- and β-subunits. Most eukaryotic organisms express multiple isotypes of α- and β-tubulin, yet their functional relevance in any organism remains largely obscure. The two α-tubulin isotypes in budding yeast, Tub1 and Tub3, are proposed to be functionally interchangeable, yet their individual functions have not been rigorously interrogated. Here, we develop otherwise isogenic yeast strains expressing single tubulin isotypes at levels comparable to total tubulin in WT cells. Using genome-wide screening, we uncover unique interactions between the isotypes and the two major mitotic spindle positioning mechanisms. We further exploit these cells to demonstrate that Tub1 and Tub3 optimize spindle positioning by differentially recruiting key components of the Dyn1- and Kar9-dependent mechanisms, respectively. Our results provide novel mechanistic insights into how tubulin isotypes allow highly conserved microtubules to function in diverse cellular processes.
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Affiliation(s)
- Emmanuel T Nsamba
- Genetics, Development, and Cell Biology, Iowa State University, Ames, IA
| | - Abesh Bera
- Genetics, Development, and Cell Biology, Iowa State University, Ames, IA
| | - Michael Costanzo
- Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
| | - Charles Boone
- Donnelly Centre, University of Toronto, Toronto, Ontario, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada.,Chemical Genomics Research Group, RIKEN Center for Sustainable Resource Sciences, Saitama, Japan
| | - Mohan L Gupta
- Genetics, Development, and Cell Biology, Iowa State University, Ames, IA
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5
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Denarier E, Ecklund KH, Berthier G, Favier A, O'Toole ET, Gory-Fauré S, De Macedo L, Delphin C, Andrieux A, Markus SM, Boscheron C. Modeling a disease-correlated tubulin mutation in budding yeast reveals insight into MAP-mediated dynein function. Mol Biol Cell 2021; 32:ar10. [PMID: 34379441 PMCID: PMC8684761 DOI: 10.1091/mbc.e21-05-0237] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mutations in the genes that encode α- and β-tubulin underlie many neurological diseases, most notably malformations in cortical development. In addition to revealing the molecular basis for disease etiology, studying such mutations can provide insight into microtubule function and the role of the large family of microtubule effectors. In this study, we use budding yeast to model one such mutation—Gly436Arg in α-tubulin, which is causative of malformations in cortical development—in order to understand how it impacts microtubule function in a simple eukaryotic system. Using a combination of in vitro and in vivo methodologies, including live cell imaging and electron tomography, we find that the mutant tubulin is incorporated into microtubules, causes a shift in α-tubulin isotype usage, and dramatically enhances dynein activity, which leads to spindle-positioning defects. We find that the basis for the latter phenotype is an impaired interaction between She1—a dynein inhibitor—and the mutant microtubules. In addition to revealing the natural balance of α-tubulin isotype utilization in cells, our results provide evidence of an impaired interaction between microtubules and a dynein regulator as a consequence of a tubulin mutation and sheds light on a mechanism that may be causative of neurodevelopmental diseases.
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Affiliation(s)
- E Denarier
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - K H Ecklund
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, United States
| | - G Berthier
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - A Favier
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - E T O'Toole
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Boulder, Colorado, United States
| | - S Gory-Fauré
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - L De Macedo
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - C Delphin
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - A Andrieux
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - S M Markus
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, United States
| | - C Boscheron
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
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6
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Cargo Release from Myosin V Requires the Convergence of Parallel Pathways that Phosphorylate and Ubiquitylate the Cargo Adaptor. Curr Biol 2020; 30:4399-4412.e7. [PMID: 32916113 DOI: 10.1016/j.cub.2020.08.062] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 07/23/2020] [Accepted: 08/17/2020] [Indexed: 11/22/2022]
Abstract
Cellular function requires molecular motors to transport cargoes to their correct intracellular locations. The regulated assembly and disassembly of motor-adaptor complexes ensures that cargoes are loaded at their origin and unloaded at their destination. In Saccharomyces cerevisiae, early in the cell cycle, a portion of the vacuole is transported into the emerging bud. This transport requires a myosin V motor, Myo2, which attaches to the vacuole via Vac17, the vacuole-specific adaptor protein. Vac17 also binds to Vac8, a vacuolar membrane protein. Once the vacuole is brought to the bud cortex via the Myo2-Vac17-Vac8 complex, Vac17 is degraded and the vacuole is released from Myo2. However, mechanisms governing dissociation of the Myo2-Vac17-Vac8 complex are not well understood. Ubiquitylation of the Vac17 adaptor at the bud cortex provides spatial regulation of vacuole release. Here, we report that ubiquitylation alone is not sufficient for cargo release. We find that a parallel pathway, which initiates on the vacuole, converges with ubiquitylation to release the vacuole from Myo2. Specifically, we show that Yck3 and Vps41, independent of their known roles in homotypic fusion and protein sorting (HOPS)-mediated vesicle tethering, are required for the phosphorylation of Vac17 in its Myo2 binding domain. These phosphorylation events allow ubiquitylated Vac17 to be released from Myo2 and Vac8. Our data suggest that Vps41 is regulating the phosphorylation of Vac17 via Yck3, a casein kinase I, and likely another unknown kinase. That parallel pathways are required to release the vacuole from Myo2 suggests that multiple signals are integrated to terminate organelle inheritance.
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7
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Cytokinesis in Eukaryotic Cells: The Furrow Complexity at a Glance. Cells 2020; 9:cells9020271. [PMID: 31979090 PMCID: PMC7072619 DOI: 10.3390/cells9020271] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 01/17/2020] [Accepted: 01/20/2020] [Indexed: 12/31/2022] Open
Abstract
The duplication cycle is the fascinating process that, starting from a cell, results in the formation of two daughter cells and it is essential for life. Cytokinesis is the final step of the cell cycle, it is a very complex phase, and is a concert of forces, remodeling, trafficking, and cell signaling. All of the steps of cell division must be properly coordinated with each other to faithfully segregate the genetic material and this task is fundamental for generating viable cells. Given the importance of this process, molecular pathways and proteins that are involved in cytokinesis are conserved from yeast to humans. In this review, we describe symmetric and asymmetric cell division in animal cell and in a model organism, budding yeast. In addition, we illustrate the surveillance mechanisms that ensure a proper cell division and discuss the connections with normal cell proliferation and organs development and with the occurrence of human diseases.
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8
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Manzano-López J, Matellán L, Álvarez-Llamas A, Blanco-Mira JC, Monje-Casas F. Asymmetric inheritance of spindle microtubule-organizing centres preserves replicative lifespan. Nat Cell Biol 2019; 21:952-965. [DOI: 10.1038/s41556-019-0364-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 06/23/2019] [Indexed: 12/19/2022]
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9
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Stahl T, Hümmer S, Ehrenfeuchter N, Mittal N, Fucile G, Spang A. Asymmetric distribution of glucose transporter mRNA provides a growth advantage in yeast. EMBO J 2019; 38:e100373. [PMID: 30910878 PMCID: PMC6517814 DOI: 10.15252/embj.2018100373] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 02/21/2019] [Accepted: 02/27/2019] [Indexed: 01/09/2023] Open
Abstract
Asymmetric localization of mRNA is important for cell fate decisions in eukaryotes and provides the means for localized protein synthesis in a variety of cell types. Here, we show that hexose transporter mRNAs are retained in the mother cell of S. cerevisiae until metaphase-anaphase transition (MAT) and then are released into the bud. The retained mRNA was translationally less active but bound to ribosomes before MAT Importantly, when cells were shifted from starvation to glucose-rich conditions, HXT2 mRNA, but none of the other HXT mRNAs, was enriched in the bud after MAT This enrichment was dependent on the Ras/cAMP/PKA pathway, the APC ortholog Kar9, and nuclear segregation into the bud. Competition experiments between strains that only expressed one hexose transporter at a time revealed that HXT2 only cells grow faster than their counterparts when released from starvation. Therefore, asymmetric distribution of HXT2 mRNA provides a growth advantage for daughters, who are better prepared for nutritional changes in the environment. Our data provide evidence that asymmetric mRNA localization is an important factor in determining cellular fitness.
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Affiliation(s)
- Timo Stahl
- Biozentrum, University of Basel, Basel, Switzerland
| | | | | | | | - Geoffrey Fucile
- SIB Swiss Institute of Bioinformatics, sciCORE Computing Center, University of Basel, Basel, Switzerland
| | - Anne Spang
- Biozentrum, University of Basel, Basel, Switzerland
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10
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Raspelli E, Fraschini R. Spindle pole power in health and disease. Curr Genet 2019; 65:851-855. [DOI: 10.1007/s00294-019-00941-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 02/05/2019] [Accepted: 02/13/2019] [Indexed: 12/27/2022]
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11
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Varshney N, Som S, Chatterjee S, Sridhar S, Bhattacharyya D, Paul R, Sanyal K. Spatio-temporal regulation of nuclear division by Aurora B kinase Ipl1 in Cryptococcus neoformans. PLoS Genet 2019; 15:e1007959. [PMID: 30763303 PMCID: PMC6392335 DOI: 10.1371/journal.pgen.1007959] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 02/27/2019] [Accepted: 01/11/2019] [Indexed: 11/29/2022] Open
Abstract
The nuclear division takes place in the daughter cell in the basidiomycetous budding yeast Cryptococcus neoformans. Unclustered kinetochores gradually cluster and the nucleus moves to the daughter bud as cells enter mitosis. Here, we show that the evolutionarily conserved Aurora B kinase Ipl1 localizes to the nucleus upon the breakdown of the nuclear envelope during mitosis in C. neoformans. Ipl1 is shown to be required for timely breakdown of the nuclear envelope as well. Ipl1 is essential for viability and regulates structural integrity of microtubules. The compromised stability of cytoplasmic microtubules upon Ipl1 depletion results in a significant delay in kinetochore clustering and nuclear migration. By generating an in silico model of mitosis, we previously proposed that cytoplasmic microtubules and cortical dyneins promote atypical nuclear division in C. neoformans. Improving the previous in silico model by introducing additional parameters, here we predict that an effective cortical bias generated by cytosolic Bim1 and dynein regulates dynamics of kinetochore clustering and nuclear migration. Indeed, in vivo alterations of Bim1 or dynein cellular levels delay nuclear migration. Results from in silico model and localization dynamics by live cell imaging suggests that Ipl1 spatio-temporally influences Bim1 or/and dynein activity along with microtubule stability to ensure timely onset of nuclear division. Together, we propose that the timely breakdown of the nuclear envelope by Ipl1 allows its own nuclear entry that helps in spatio-temporal regulation of nuclear division during semi-open mitosis in C. neoformans. Unlike the model ascomycetous budding yeast Saccharomyces cerevisiae, microtubule organizing centers (MTOCs) coalesce to form the spindle pole body (SPB) in C. neoformans. This process also ensures unclustered kinetochores to gradually cluster in this organism. As C. neoformans cells enter mitosis, the nuclear envelope ruptures and the nucleus eventually moves to the daughter bud before division. Here, we combine cell and systems biology techniques to understand the key determinants of nuclear division in C. neoformans. We show that the evolutionarily conserved Aurora B kinase Ipl1 enters the nucleus during the mitotic phase as cells undergo semi-open mitosis. Ipl1 regulates dynamics of cytoplasmic microtubules, cytosolic proteins such as Bim1 and dynein-mediated cortical forces and integrity of the nuclear envelope to ensure timely kinetochore clustering and nuclear division in this medically relevant human pathogenic budding yeast.
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Affiliation(s)
- Neha Varshney
- Molecular Mycology Laboratory, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, India
| | - Subhendu Som
- Department of Solid State Physics, Indian Association for the Cultivation of Science, Kolkata, India
| | - Saptarshi Chatterjee
- Department of Solid State Physics, Indian Association for the Cultivation of Science, Kolkata, India
| | - Shreyas Sridhar
- Molecular Mycology Laboratory, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, India
| | - Dibyendu Bhattacharyya
- Tata Memorial Centre, Advanced Centre for Treatment Research and Education in Cancer, Kharghar, Navi Mumbai, India
| | - Raja Paul
- Department of Solid State Physics, Indian Association for the Cultivation of Science, Kolkata, India
- * E-mail: (RP); (KS)
| | - Kaustuv Sanyal
- Molecular Mycology Laboratory, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, India
- * E-mail: (RP); (KS)
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12
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Denarier E, Brousse C, Sissoko A, Andrieux A, Boscheron C. A neurodevelopmental TUBB2B β-tubulin mutation impairs Bim1 (yeast EB1)-dependent spindle positioning. Biol Open 2019; 8:bio.038620. [PMID: 30674462 PMCID: PMC6361202 DOI: 10.1242/bio.038620] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Malformations of the human cerebral cortex can be caused by mutations in tubulins that associate to compose microtubules. Cerebral cortical folding relies on neuronal migration and on progenitor proliferation partly dictated by microtubule-dependent mitotic spindle positioning. A single amino acid change, F265L, in the conserved TUBB2B β-tubulin gene has been identified in patients with abnormal cortex formation. A caveat for studying this mutation in mammalian cells is that nine genes encode β-tubulin in human. Here, we generate a yeast strain expressing F265L tubulin mutant as the sole source of β-tubulin. The F265L mutation does not preclude expression of a stable β-tubulin protein which is incorporated into microtubules. However, impaired cell growth was observed at high temperatures along with altered microtubule dynamics and stability. In addition, F265L mutation produces a highly specific mitotic spindle positioning defect related to Bim1 (yeast EB1) dysfunction. Indeed, F265L cells display an abnormal Bim1 recruitment profile at microtubule plus-ends. These results indicate that the F265L β-tubulin mutation affects microtubule plus-end complexes known to be important for microtubule dynamics and for microtubule function during mitotic spindle positioning.
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Affiliation(s)
- Eric Denarier
- Univ. Grenoble Alpes, Grenoble Institut des Neurosciences, GIN, F-38000, Grenoble, France.,Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38000, Grenoble, France.,Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Biosciences and Biotechnology Institute of Grenoble, Grenoble, France
| | - Carine Brousse
- Institut National de la Transfusion Sanguine (INTS), F-75015 Paris, France
| | | | - Annie Andrieux
- Univ. Grenoble Alpes, Grenoble Institut des Neurosciences, GIN, F-38000, Grenoble, France.,Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38000, Grenoble, France.,Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Biosciences and Biotechnology Institute of Grenoble, Grenoble, France
| | - Cécile Boscheron
- Univ. Grenoble Alpes, Grenoble Institut des Neurosciences, GIN, F-38000, Grenoble, France .,Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38000, Grenoble, France.,Institut de Biologie Structurale (IBS) , F-38000 Grenoble, France
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13
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Fraschini R. Divide Precisely and Proliferate Safely: Lessons From Budding Yeast. Front Genet 2019; 9:738. [PMID: 30687396 PMCID: PMC6335322 DOI: 10.3389/fgene.2018.00738] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 12/22/2018] [Indexed: 12/16/2022] Open
Abstract
A faithful cell division is essential for proper cellular proliferation of all eukaryotic cells; indeed the correct segregation of the genetic material allows daughter cells to proceed into the cell cycle safely. Conversely, errors during chromosome partition generate aneuploid cells that have been associated to several human pathological conditions, including cancer. Given the importance of this issue, all the steps that lead to cell separation are finely regulated. The budding yeast Saccharomyces cerevisiae is a unicellular eukaryotic organism that divides asymmetrically and it is a suitable model system to study the regulation of cell division. Humans and budding yeast are distant 1 billion years of evolution, nonetheless several essential pathways, proteins, and cellular structures are conserved. Among these, the mitotic spindle is a key player in chromosome segregation and its correct morphogenesis and functioning is essential for genomic stability. In this review we will focus on molecular pathways and proteins involved in the control mitotic spindle morphogenesis and function that are conserved from yeast to humans and whose impairment is connected with the development of human diseases.
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Affiliation(s)
- Roberta Fraschini
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milan, Italy
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14
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The Tubulin Detyrosination Cycle: Function and Enzymes. Trends Cell Biol 2019; 29:80-92. [DOI: 10.1016/j.tcb.2018.08.003] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 08/14/2018] [Accepted: 08/15/2018] [Indexed: 12/24/2022]
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15
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Raspelli E, Facchinetti S, Fraschini R. Swe1 and Mih1 regulate mitotic spindle dynamics in budding yeast via Bik1. J Cell Sci 2018; 131:jcs.213520. [PMID: 30072442 DOI: 10.1242/jcs.213520] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 07/11/2018] [Indexed: 12/20/2022] Open
Abstract
The mitotic spindle is a very dynamic structure that is built de novo and destroyed at each round of cell division. In order to perform its fundamental function during chromosome segregation, mitotic spindle dynamics must be tightly coordinated with other cell cycle events. These changes are driven by several protein kinases, phosphatases and microtubule-associated proteins. In budding yeast, the kinase Swe1 and the phosphatase Mih1 act in concert in controlling the phosphorylation state of Cdc28, the catalytic subunit of Cdk1, the major regulator of the cell cycle. In this study we show that Swe1 and Mih1 are also involved in the control of mitotic spindle dynamics. Our data indicate that Swe1 and the Polo-like kinase Cdc5 control the balance between phosphorylated and unphosphorylated forms of Mih1, which is, in turn, important for mitotic spindle elongation. Moreover, we show that the microtubule-associated protein Bik1 is a phosphoprotein, and that Swe1 and Mih1 are both involved in controlling phosphorylation of Bik1. These results uncover new players and provide insights into the complex regulation of mitotic spindle dynamics.
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Affiliation(s)
- Erica Raspelli
- Università degli Studi di Milano-Bicocca, Dipartimento di Biotecnologie e Bioscienze, Piazza della Scienza 2, 20126 Milano, Italy
| | - Silvia Facchinetti
- Università degli Studi di Milano-Bicocca, Dipartimento di Biotecnologie e Bioscienze, Piazza della Scienza 2, 20126 Milano, Italy
| | - Roberta Fraschini
- Università degli Studi di Milano-Bicocca, Dipartimento di Biotecnologie e Bioscienze, Piazza della Scienza 2, 20126 Milano, Italy
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16
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Molines AT, Marion J, Chabout S, Besse L, Dompierre JP, Mouille G, Coquelle FM. EB1 contributes to microtubule bundling and organization, along with root growth, in Arabidopsis thaliana. Biol Open 2018; 7:bio.030510. [PMID: 29945874 PMCID: PMC6124560 DOI: 10.1242/bio.030510] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Microtubules are involved in plant development and adaptation to their environment, but the sustaining molecular mechanisms remain elusive. Microtubule-end-binding 1 (EB1) proteins participate in directional root growth in Arabidopsis thaliana. However, a connection to the underlying microtubule array has not been established yet. We show here that EB1 proteins contribute to the organization of cortical microtubules in growing epidermal plant cells, without significant modulation of microtubule dynamics. Using super-resolution stimulated emission depletion (STED) microscopy and an original quantification approach, we also demonstrate a significant reduction of apparent microtubule bundling in cytoplasmic-EB1-deficient plants, suggesting a function for EB1 in the interaction between adjacent microtubules. Furthermore, we observed root growth defects in EB1-deficient plants, which are not related to cell division impairment. Altogether, our results support a role for EB1 proteins in root development, in part by maintaining the organization of cortical microtubules. This article has an associated First Person interview with the first author of the paper. Summary: EB1 proteins affect cortical-microtubule bundling and organization in Arabidopsis thaliana, without significant modulation of microtubule dynamics. They also participate in root growth, further linking microtubules to plant development.
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Affiliation(s)
- Arthur T Molines
- Department of Cell Biology, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette Cedex, France
| | - Jessica Marion
- Department of Cell Biology, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette Cedex, France
| | - Salem Chabout
- Institut Jean-Pierre Bourgin (IJPB), INRA - AgroParisTech, 78026 Versailles Cedex, France
| | - Laetitia Besse
- Light Microscopy Facility, Imagerie-Gif, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette Cedex, France
| | - Jim P Dompierre
- Light Microscopy Facility, Imagerie-Gif, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette Cedex, France
| | - Grégory Mouille
- Institut Jean-Pierre Bourgin (IJPB), INRA - AgroParisTech, 78026 Versailles Cedex, France
| | - Frédéric M Coquelle
- Department of Cell Biology, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette Cedex, France
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17
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Lengefeld J, Barral Y. Asymmetric Segregation of Aged Spindle Pole Bodies During Cell Division: Mechanisms and Relevance Beyond Budding Yeast? Bioessays 2018; 40:e1800038. [DOI: 10.1002/bies.201800038] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 05/21/2018] [Indexed: 01/21/2023]
Affiliation(s)
- Jette Lengefeld
- Institute of Biochemistry; ETH Zurich; Otto-Stern-Weg 3 8093 Zurich Switzerland
- David H. Koch Institute for Integrative Cancer Research; Massachusetts Institute of Technology; Cambridge, Massachusetts 02139 USA
| | - Yves Barral
- Institute of Biochemistry; ETH Zurich; Otto-Stern-Weg 3 8093 Zurich Switzerland
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18
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Greenlee M, Alonso A, Rahman M, Meednu N, Davis K, Tabb V, Cook R, Miller RK. The TOG protein Stu2/XMAP215 interacts covalently and noncovalently with SUMO. Cytoskeleton (Hoboken) 2018; 75:290-306. [PMID: 29729126 PMCID: PMC6712953 DOI: 10.1002/cm.21449] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 04/27/2018] [Accepted: 04/30/2018] [Indexed: 01/21/2023]
Abstract
Stu2p is the yeast member of the XMAP215/Dis1/ch‐TOG family of microtubule‐associated proteins that promote microtubule polymerization. However, the factors that regulate its activity are not clearly understood. Here we report that Stu2p in the budding yeast Saccharomyces cerevisiae interacts with SUMO by covalent and noncovalent mechanisms. Stu2p interacted by two‐hybrid analysis with the yeast SUMO Smt3p, its E2 Ubc9p, and the E3 Nfi1p. A region of Stu2p containing the dimerization domain was both necessary and sufficient for interaction with SUMO and Ubc9p. Stu2p was found to be sumoylated both in vitro and in vivo. Stu2p copurified with SUMO in a pull‐down assay and vice versa. Stu2p also bound to a nonconjugatable form of SUMO, suggesting that Stu2p can interact noncovalently with SUMO. In addition, Stu2p interacted with the STUbL enzyme Ris1p. Stu2p also copurified with ubiquitin in a pull‐down assay, suggesting that it can be modified by both SUMO and ubiquitin. Tubulin, a major binding partner of Stu2p, also interacted noncovalently with SUMO. By two‐hybrid analysis, the beta‐tubulin Tub2p interacted with SUMO independently of the microtubule stressor, benomyl. Together, these findings raise the possibility that the microtubule polymerization activities mediated by Stu2p are regulated through sumoylation pathways.
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Affiliation(s)
- Matt Greenlee
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, 74078
| | - Annabel Alonso
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, 74078
| | - Maliha Rahman
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, 74078
| | - Nida Meednu
- Department of Biology, University of Rochester, Rochester, New York, 14627
| | - Kayla Davis
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, 74078
| | - Victoria Tabb
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, 74078
| | - River Cook
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, 74078
| | - Rita K Miller
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, 74078
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19
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Heppert JK, Pani AM, Roberts AM, Dickinson DJ, Goldstein B. A CRISPR Tagging-Based Screen Reveals Localized Players in Wnt-Directed Asymmetric Cell Division. Genetics 2018; 208:1147-1164. [PMID: 29348144 PMCID: PMC5844328 DOI: 10.1534/genetics.117.300487] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 01/08/2018] [Indexed: 11/18/2022] Open
Abstract
Oriented cell divisions are critical to establish and maintain cell fates and tissue organization. Diverse extracellular and intracellular cues have been shown to provide spatial information for mitotic spindle positioning; however, the molecular mechanisms by which extracellular signals communicate with cells to direct mitotic spindle positioning are largely unknown. In animal cells, oriented cell divisions are often achieved by the localization of force-generating motor protein complexes to discrete cortical domains. Disrupting either these force-generating complexes or proteins that globally affect microtubule stability results in defects in mitotic positioning, irrespective of whether these proteins function as spatial cues for spindle orientation. This poses a challenge to traditional genetic dissection of this process. Therefore, as an alternative strategy to identify key proteins that act downstream of intercellular signaling, we screened the localization of many candidate proteins by inserting fluorescent tags directly into endogenous gene loci, without overexpressing the proteins. We tagged 23 candidate proteins in Caenorhabditis elegans and examined each protein's localization in a well-characterized, oriented cell division in the four-cell-stage embryo. We used cell manipulations and genetic experiments to determine which cells harbor key localized proteins and which signals direct these localizations in vivo We found that Dishevelled and adenomatous polyposis coli homologs are polarized during this oriented cell division in response to a Wnt signal, but two proteins typically associated with mitotic spindle positioning, homologs of NuMA and Dynein, were not detectably polarized. These results suggest an unexpected mechanism for mitotic spindle positioning in this system, they pinpoint key proteins of interest, and they highlight the utility of a screening approach based on analyzing the localization of endogenously tagged proteins.
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Affiliation(s)
- Jennifer K Heppert
- Department of Biology, University of North Carolina at Chapel Hill, North Carolina 27599
| | - Ariel M Pani
- Department of Biology, University of North Carolina at Chapel Hill, North Carolina 27599
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, North Carolina 27599
| | - Allyson M Roberts
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, North Carolina 27599
| | - Daniel J Dickinson
- Department of Biology, University of North Carolina at Chapel Hill, North Carolina 27599
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, North Carolina 27599
| | - Bob Goldstein
- Department of Biology, University of North Carolina at Chapel Hill, North Carolina 27599
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, North Carolina 27599
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, North Carolina 27599
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20
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Sugioka K, Fielmich LE, Mizumoto K, Bowerman B, van den Heuvel S, Kimura A, Sawa H. Tumor suppressor APC is an attenuator of spindle-pulling forces during C. elegans asymmetric cell division. Proc Natl Acad Sci U S A 2018; 115:E954-E963. [PMID: 29348204 PMCID: PMC5798331 DOI: 10.1073/pnas.1712052115] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The adenomatous polyposis coli (APC) tumor suppressor has dual functions in Wnt/β-catenin signaling and accurate chromosome segregation and is frequently mutated in colorectal cancers. Although APC contributes to proper cell division, the underlying mechanisms remain poorly understood. Here we show that Caenorhabditis elegans APR-1/APC is an attenuator of the pulling forces acting on the mitotic spindle. During asymmetric cell division of the C. elegans zygote, a LIN-5/NuMA protein complex localizes dynein to the cell cortex to generate pulling forces on astral microtubules that position the mitotic spindle. We found that APR-1 localizes to the anterior cell cortex in a Par-aPKC polarity-dependent manner and suppresses anterior centrosome movements. Our combined cell biological and mathematical analyses support the conclusion that cortical APR-1 reduces force generation by stabilizing microtubule plus-ends at the cell cortex. Furthermore, APR-1 functions in coordination with LIN-5 phosphorylation to attenuate spindle-pulling forces. Our results document a physical basis for the attenuation of spindle-pulling force, which may be generally used in asymmetric cell division and, when disrupted, potentially contributes to division defects in cancer.
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Affiliation(s)
- Kenji Sugioka
- Multicellular Organization Laboratory, National Institute of Genetics, 411-8540 Mishima, Japan
- RIKEN Center for Developmental Biology, Chuo-ku, 650-0047 Kobe, Japan
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403
| | - Lars-Eric Fielmich
- Developmental Biology, Biology Department, Science 4 Life, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Kota Mizumoto
- RIKEN Center for Developmental Biology, Chuo-ku, 650-0047 Kobe, Japan
| | - Bruce Bowerman
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403
| | - Sander van den Heuvel
- Developmental Biology, Biology Department, Science 4 Life, Utrecht University, 3584 CH Utrecht, The Netherlands;
| | - Akatsuki Kimura
- Cell Architecture Laboratory, National Institute of Genetics, 411-8540 Mishima, Japan;
- Department of Genetics, School of Life Science, Sokendai, 411-8540 Mishima, Japan
| | - Hitoshi Sawa
- Multicellular Organization Laboratory, National Institute of Genetics, 411-8540 Mishima, Japan;
- RIKEN Center for Developmental Biology, Chuo-ku, 650-0047 Kobe, Japan
- Department of Genetics, School of Life Science, Sokendai, 411-8540 Mishima, Japan
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21
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Xiang X. Nuclear movement in fungi. Semin Cell Dev Biol 2017; 82:3-16. [PMID: 29241689 DOI: 10.1016/j.semcdb.2017.10.024] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 10/17/2017] [Accepted: 10/23/2017] [Indexed: 12/22/2022]
Abstract
Nuclear movement within a cell occurs in a variety of eukaryotic organisms including yeasts and filamentous fungi. Fungal molecular genetic studies identified the minus-end-directed microtubule motor cytoplasmic dynein as a critical protein for nuclear movement or orientation of the mitotic spindle contained in the nucleus. Studies in the budding yeast first indicated that dynein anchored at the cortex via its anchoring protein Num1 exerts pulling force on an astral microtubule to orient the anaphase spindle across the mother-daughter axis before nuclear division. Prior to anaphase, myosin V interacts with the plus end of an astral microtubule via Kar9-Bim1/EB1 and pulls the plus end along the actin cables to move the nucleus/spindle close to the bud neck. In addition, pushing or pulling forces generated from cortex-linked polymerization or depolymerization of microtubules drive nuclear movements in yeasts and possibly also in filamentous fungi. In filamentous fungi, multiple nuclei within a hyphal segment undergo dynein-dependent back-and-forth movements and their positioning is also influenced by cytoplasmic streaming toward the hyphal tip. In addition, nuclear movement occurs at various stages of fungal development and fungal infection of plant tissues. This review discusses our current understanding on the mechanisms of nuclear movement in fungal organisms, the importance of nuclear positioning and the regulatory strategies that ensure the proper positioning of nucleus/spindle.
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Affiliation(s)
- Xin Xiang
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences - F. Edward Hébert School of Medicine, Bethesda, MD, USA.
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22
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Barsegov V, Ross JL, Dima RI. Dynamics of microtubules: highlights of recent computational and experimental investigations. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:433003. [PMID: 28812545 DOI: 10.1088/1361-648x/aa8670] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Microtubules are found in most eukaryotic cells, with homologs in eubacteria and archea, and they have functional roles in mitosis, cell motility, intracellular transport, and the maintenance of cell shape. Numerous efforts have been expended over the last two decades to characterize the interactions between microtubules and the wide variety of microtubule associated proteins that control their dynamic behavior in cells resulting in microtubules being assembled and disassembled where and when they are required by the cell. We present the main findings regarding microtubule polymerization and depolymerization and review recent work about the molecular motors that modulate microtubule dynamics by inducing either microtubule depolymerization or severing. We also discuss the main experimental and computational approaches used to quantify the thermodynamics and mechanics of microtubule filaments.
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Affiliation(s)
- Valeri Barsegov
- Department of Chemistry, University of Massachusetts, Lowell, MA 01854, United States of America
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23
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She ZY, Yang WX. Molecular mechanisms of kinesin-14 motors in spindle assembly and chromosome segregation. J Cell Sci 2017; 130:2097-2110. [DOI: 10.1242/jcs.200261] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
ABSTRACT
During eukaryote cell division, molecular motors are crucial regulators of microtubule organization, spindle assembly, chromosome segregation and intracellular transport. The kinesin-14 motors are evolutionarily conserved minus-end-directed kinesin motors that occur in diverse organisms from simple yeasts to higher eukaryotes. Members of the kinesin-14 motor family can bind to, crosslink or slide microtubules and, thus, regulate microtubule organization and spindle assembly. In this Commentary, we present the common subthemes that have emerged from studies of the molecular kinetics and mechanics of kinesin-14 motors, particularly with regard to their non-processive movement, their ability to crosslink microtubules and interact with the minus- and plus-ends of microtubules, and with microtubule-organizing center proteins. In particular, counteracting forces between minus-end-directed kinesin-14 and plus-end-directed kinesin-5 motors have recently been implicated in the regulation of microtubule nucleation. We also discuss recent progress in our current understanding of the multiple and fundamental functions that kinesin-14 motors family members have in important aspects of cell division, including the spindle pole, spindle organization and chromosome segregation.
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Affiliation(s)
- Zhen-Yu She
- The Sperm Laboratory, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Wan-Xi Yang
- The Sperm Laboratory, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
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24
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Liu Z, Wu S, Chen Y, Han X, Gu Q, Yin Y, Ma Z. The microtubule end-binding protein FgEB1 regulates polar growth and fungicide sensitivity via different interactors in Fusarium graminearum. Environ Microbiol 2017; 19:1791-1807. [PMID: 28028881 DOI: 10.1111/1462-2920.13651] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 12/18/2016] [Indexed: 11/30/2022]
Abstract
In yeasts, the end-binding protein 1 (EB1) homologs regulate microtubule dynamics, cell polarization, and chromosome stability. However, functions of EB1 orthologs in plant pathogenic fungi have not been characterized yet. Here, we observed that the FgEB1 deletion mutant (ΔFgEB1) of Fusarium graminearum exhibits twisted hyphae, increased hyphal branching and curved conidia, indicating that FgEB1 is involved in the regulation of cellular polarity. Microscopic examination further showed that the microtubules of ΔFgEB1 exhibited less organized in comparison with those of the wild type. In addition, the lack of FgEB1 also altered the distribution of polarity-related class I myosin via the interaction with the actin. On the other hand, we identified four core septins as FgEB1-interacting proteins, and found that FgEB1 and septins regulated conidial polar growth in the opposite orientation. Interestingly, FgEB1 and FgKar9 constituted another complex that modulated the response to carbendazim, a microtubule-damaging agent specifically. In addition, the deletion of FgEB1 led to dramatically decreased deoxynivalenol (DON) biosynthesis. Taken together, results of this study indicate that FgEB1 regulates cellular polarity, fungicide sensitivity and DON biosynthesis via different interactors in F. graminarum, which provides a novel insight into understanding of the biological functions of EB1 in filamentous fungi.
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Affiliation(s)
- Zunyong Liu
- Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Sisi Wu
- Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Yun Chen
- Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Xinyue Han
- Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Qin Gu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yanni Yin
- Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
| | - Zhonghua Ma
- Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China.,State Key Laboratory of Rice Biology, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, China
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25
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Li Y, Li W, Liang B, Li L, Wang L, Huang H, Guo S, Wang Y, He Y, Chen L, He W. Identification of cancer risk lncRNAs and cancer risk pathways regulated by cancer risk lncRNAs based on genome sequencing data in human cancers. Sci Rep 2016; 6:39294. [PMID: 27991568 PMCID: PMC5171637 DOI: 10.1038/srep39294] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 11/21/2016] [Indexed: 01/07/2023] Open
Abstract
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. The complexity of cancer can be reduced to a small number of underlying principles like cancer hallmarks which could govern the transformation of normal cells to cancer. Besides, the growth and metastasis of cancer often relate to combined effects of long non-coding RNAs (lncRNAs). Here, we performed comprehensive analysis for lncRNA expression profiles and clinical data of six types of human cancer patients from The Cancer Genome Atlas (TCGA), and identified six risk pathways and twenty three lncRNAs. In addition, twenty three cancer risk lncRNAs which were closely related to the occurrence or development of cancer had a good classification performance for samples of testing datasets of six cancer datasets. More important, these lncRNAs were able to separate samples in the entire cancer dataset into high-risk group and low-risk group with significantly different overall survival (OS), which was further validated in ten validation datasets. In our study, the robust and effective cancer biomarkers were obtained from cancer datasets which had information of normal-tumor samples. Overall, our research can provide a new perspective for the further study of clinical diagnosis and treatment of cancer.
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Affiliation(s)
- Yiran Li
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin, Hei Longjiang Province, Postal code: 150081, China
| | - Wan Li
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin, Hei Longjiang Province, Postal code: 150081, China
| | - Binhua Liang
- National Microbology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Liansheng Li
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin, Hei Longjiang Province, Postal code: 150081, China
| | - Li Wang
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin, Hei Longjiang Province, Postal code: 150081, China
| | - Hao Huang
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin, Hei Longjiang Province, Postal code: 150081, China
| | - Shanshan Guo
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin, Hei Longjiang Province, Postal code: 150081, China
| | - Yahui Wang
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin, Hei Longjiang Province, Postal code: 150081, China
| | - Yuehan He
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin, Hei Longjiang Province, Postal code: 150081, China
| | - Lina Chen
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin, Hei Longjiang Province, Postal code: 150081, China
| | - Weiming He
- Institute of Opto-electronics, Harbin Institute of Technology, Harbin, Heilongjiang Province, Postal code: 150081, China
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26
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Schweiggert J, Panigada D, Tan AN, Liakopoulos D. Kar9 controls the nucleocytoplasmic distribution of yeast EB1. Cell Cycle 2016; 15:2860-2866. [PMID: 27625073 DOI: 10.1080/15384101.2016.1231282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The precise temporal and spatial concentration of microtubule-associated proteins (MAPs) within the cell is fundamental to ensure chromosome segregation and correct spindle positioning. MAPs form an intricate web of interactions among each other and compete for binding sites on microtubules. Therefore, when assessing cellular phenotypes upon MAP up- or downregulation, it is important to consider the protein interaction network between individual MAPs. Here, we show that changes in the amounts of the spindle positioning factor Kar9 specifically affect the distribution of yeast EB1 on spindle microtubules, without influencing other microtubule-associated interacting partners of Kar9, i.e. yeast XMAP215 and CLIP-170. Alterations in the distribution of yeast EB1 explain chromosome segregation defects upon knockout, overexpression or stabilization of Kar9 and provide an example for non-linear effects on MAP behavior after perturbation of their equilibrium.
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Affiliation(s)
- Jörg Schweiggert
- a Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), CNRS UMR 523 , Montpellier , France.,b Biochemistry Centre Heidelberg (BZH) , Heidelberg , Germany.,c The Hartmut Hoffmann-Berling International Graduate School of Molecular and Cellular Biology, University of Heidelberg , Heidelberg , Germany
| | - Davide Panigada
- a Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), CNRS UMR 523 , Montpellier , France
| | - Ann Na Tan
- b Biochemistry Centre Heidelberg (BZH) , Heidelberg , Germany
| | - Dimitris Liakopoulos
- a Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), CNRS UMR 523 , Montpellier , France.,c The Hartmut Hoffmann-Berling International Graduate School of Molecular and Cellular Biology, University of Heidelberg , Heidelberg , Germany
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27
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Manatschal C, Farcas AM, Degen MS, Bayer M, Kumar A, Landgraf C, Volkmer R, Barral Y, Steinmetz MO. Molecular basis of Kar9-Bim1 complex function during mating and spindle positioning. Mol Biol Cell 2016; 27:mbc.E16-07-0552. [PMID: 27682587 PMCID: PMC5170556 DOI: 10.1091/mbc.e16-07-0552] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 09/20/2016] [Accepted: 09/21/2016] [Indexed: 11/17/2022] Open
Abstract
The Kar9 pathway promotes nuclear fusion during mating and spindle alignment during metaphase in budding yeast. How Kar9 supports the different outcome of these two divergent processes is an open question. Here, we show that three sites in the C-terminal disordered domain of Kar9 mediate tight Kar9 interaction with the C-terminal dimerization domain of Bim1 (EB1 orthologue). Site1 and Site2 contain SxIP motifs; however, Site3 defines a novel type of EB1-binding site. Whereas Site2 and Site3 mediate Kar9 recruitment to microtubule tips, nuclear movement and karyogamy, solely Site2 functions in spindle positioning during metaphase. Site1 in turn plays an inhibitory role during mating. Additionally, the Kar9-Bim1 complex is involved in microtubule-independent activities during mating. Together, our data reveal how multiple and partially redundant EB1-binding sites provide a microtubule-associated protein with the means to modulate its biochemical properties to promote different molecular processes during cell proliferation and differentiation.
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Affiliation(s)
- Cristina Manatschal
- Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, Villigen PSI, Switzerland
| | - Ana-Maria Farcas
- Institute of Biochemistry, Biology Department, ETH Zürich, Zürich, Switzerland
| | - Miriam Steiner Degen
- Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, Villigen PSI, Switzerland
| | - Mathias Bayer
- Institute of Biochemistry, Biology Department, ETH Zürich, Zürich, Switzerland
| | - Anil Kumar
- Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, Villigen PSI, Switzerland
| | - Christiane Landgraf
- Institut für Medizinische Immunologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Rudolf Volkmer
- Institut für Medizinische Immunologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Yves Barral
- Institute of Biochemistry, Biology Department, ETH Zürich, Zürich, Switzerland
| | - Michel O Steinmetz
- Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, Villigen PSI, Switzerland
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Regulation of a Spindle Positioning Factor at Kinetochores by SUMO-Targeted Ubiquitin Ligases. Dev Cell 2016; 36:415-27. [PMID: 26906737 DOI: 10.1016/j.devcel.2016.01.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 12/04/2015] [Accepted: 01/14/2016] [Indexed: 12/17/2022]
Abstract
Correct function of the mitotic spindle requires balanced interplay of kinetochore and astral microtubules that mediate chromosome segregation and spindle positioning, respectively. Errors therein can cause severe defects ranging from aneuploidy to developmental disorders. Here, we describe a protein degradation pathway that functionally links astral microtubules to kinetochores via regulation of a microtubule-associated factor. We show that the yeast spindle positioning protein Kar9 localizes not only to astral but also to kinetochore microtubules, where it becomes targeted for proteasomal degradation by the SUMO-targeted ubiquitin ligases (STUbLs) Slx5-Slx8. Intriguingly, this process does not depend on preceding sumoylation of Kar9 but rather requires SUMO-dependent recruitment of STUbLs to kinetochores. Failure to degrade Kar9 leads to defects in both chromosome segregation and spindle positioning. We propose that kinetochores serve as platforms to recruit STUbLs in a SUMO-dependent manner in order to ensure correct spindle function by regulating levels of microtubule-associated proteins.
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29
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Phosphorylation of EB2 by Aurora B and CDK1 ensures mitotic progression and genome stability. Nat Commun 2016; 7:11117. [PMID: 27030108 PMCID: PMC4821873 DOI: 10.1038/ncomms11117] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 02/22/2016] [Indexed: 02/07/2023] Open
Abstract
Temporal regulation of microtubule dynamics is essential for proper progression of mitosis and control of microtubule plus-end tracking proteins by phosphorylation is an essential component of this regulation. Here we show that Aurora B and CDK1 phosphorylate microtubule end-binding protein 2 (EB2) at multiple sites within the amino terminus and a cluster of serine/threonine residues in the linker connecting the calponin homology and end-binding homology domains. EB2 phosphorylation, which is strictly associated with mitotic entry and progression, reduces the binding affinity of EB2 for microtubules. Expression of non-phosphorylatable EB2 induces stable kinetochore microtubule dynamics and delays formation of bipolar metaphase plates in a microtubule binding-dependent manner, and leads to aneuploidy even in unperturbed mitosis. We propose that Aurora B and CDK1 temporally regulate the binding affinity of EB2 for microtubules, thereby ensuring kinetochore microtubule dynamics, proper mitotic progression and genome stability. Temporal regulation of microtubule dynamics in mitosis can be achieved by phosphorylation of microtubule plus-end proteins. Here, the authors show that Aurora B and CDK1 phosphorylate EB2, which changes microtubule binding affinity and controls kinetochore microtubule dynamics and genome stability.
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30
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Tuncay H, Ebnet K. Cell adhesion molecule control of planar spindle orientation. Cell Mol Life Sci 2016; 73:1195-207. [PMID: 26698907 PMCID: PMC11108431 DOI: 10.1007/s00018-015-2116-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 11/26/2015] [Accepted: 12/10/2015] [Indexed: 12/22/2022]
Abstract
Polarized epithelial cells align the mitotic spindle in the plane of the sheet to maintain tissue integrity and to prevent malignant transformation. The orientation of the spindle apparatus is regulated by the immobilization of the astral microtubules at the lateral cortex and depends on the precise localization of the dynein-dynactin motor protein complex which captures microtubule plus ends and generates pulling forces towards the centrosomes. Recent developments indicate that signals derived from intercellular junctions are required for the stable interaction of the dynein-dynactin complex with the cortex. Here, we review the molecular mechanisms that regulate planar spindle orientation in polarized epithelial cells and we illustrate how different cell adhesion molecules through distinct and non-overlapping mechanisms instruct the cells to align the mitotic spindle in the plane of the sheet.
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Affiliation(s)
- Hüseyin Tuncay
- Institute-Associated Research Group "Cell Adhesion and Cell Polarity", Institute of Medical Biochemistry, ZMBE, University of Münster, Von-Esmarch-Str. 56, 48149, Muenster, Germany
| | - Klaus Ebnet
- Institute-Associated Research Group "Cell Adhesion and Cell Polarity", Institute of Medical Biochemistry, ZMBE, University of Münster, Von-Esmarch-Str. 56, 48149, Muenster, Germany.
- Interdisciplinary Clinical Research Center (IZKF), University of Münster, 48419, Muenster, Germany.
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31
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Chen CT, Kelly M, Leon JD, Nwagbara B, Ebbert P, Ferguson DJP, Lowery LA, Morrissette N, Gubbels MJ. Compartmentalized Toxoplasma EB1 bundles spindle microtubules to secure accurate chromosome segregation. Mol Biol Cell 2015; 26:4562-76. [PMID: 26466679 PMCID: PMC4678015 DOI: 10.1091/mbc.e15-06-0437] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 10/02/2015] [Indexed: 11/11/2022] Open
Abstract
The opportunistic apicomplexan parasite Toxoplasma gondii divides by intertwined closed mitosis and internal budding. Centrosome positioning and MT acetylation control spindle dynamics, and the MT-associated protein TgEB1 residing in the nucleus contributes to mitotic fidelity by bundling the spindle MTs. Toxoplasma gondii replicates asexually by a unique internal budding process characterized by interwoven closed mitosis and cytokinesis. Although it is known that the centrosome coordinates these processes, the spatiotemporal organization of mitosis remains poorly defined. Here we demonstrate that centrosome positioning around the nucleus may signal spindle assembly: spindle microtubules (MTs) are first assembled when the centrosome moves to the basal side and become extensively acetylated after the duplicated centrosomes reposition to the apical side. We also tracked the spindle MTs using the MT plus end–binding protein TgEB1. Endowed by a C-terminal NLS, TgEB1 resides in the nucleoplasm in interphase and associates with the spindle MTs during mitosis. TgEB1 also associates with the subpellicular MTs at the growing end of daughter buds toward the completion of karyokinesis. Depletion of TgEB1 results in escalated disintegration of kinetochore clustering. Furthermore, we show that TgEB1’s MT association in Toxoplasma and in a heterologous system (Xenopus) is based on the same principles. Finally, overexpression of a high-MT-affinity TgEB1 mutant promotes the formation of overstabilized MT bundles, resulting in avulsion of otherwise tightly clustered kinetochores. Overall we conclude that centrosome position controls spindle activity and that TgEB1 is critical for mitotic integrity.
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Affiliation(s)
- Chun-Ti Chen
- Department of Biology, Boston College, Chestnut Hill, MA 02467
| | - Megan Kelly
- Department of Biology, Boston College, Chestnut Hill, MA 02467
| | - Jessica de Leon
- Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA 92697
| | | | - Patrick Ebbert
- Department of Biology, Boston College, Chestnut Hill, MA 02467
| | - David J P Ferguson
- Nuffield Department of Clinical Laboratory Science, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom
| | | | - Naomi Morrissette
- Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA 92697
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32
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Sutradhar S, Yadav V, Sridhar S, Sreekumar L, Bhattacharyya D, Ghosh SK, Paul R, Sanyal K. A comprehensive model to predict mitotic division in budding yeasts. Mol Biol Cell 2015; 26:3954-65. [PMID: 26310442 PMCID: PMC4710229 DOI: 10.1091/mbc.e15-04-0236] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 08/14/2015] [Indexed: 12/26/2022] Open
Abstract
A mechanistic in silico model predicts mitotic events and effects of perturbation in budding yeasts belonging to Ascomycota and Basidiomycota. The model identifies distinct pathways based on the population of cytoplasmic microtubules and cortical dyneins as determinants of nuclear and spindle positioning in these phyla. High-fidelity chromosome segregation during cell division depends on a series of concerted interdependent interactions. Using a systems biology approach, we built a robust minimal computational model to comprehend mitotic events in dividing budding yeasts of two major phyla: Ascomycota and Basidiomycota. This model accurately reproduces experimental observations related to spindle alignment, nuclear migration, and microtubule (MT) dynamics during cell division in these yeasts. The model converges to the conclusion that biased nucleation of cytoplasmic microtubules (cMTs) is essential for directional nuclear migration. Two distinct pathways, based on the population of cMTs and cortical dyneins, differentiate nuclear migration and spindle orientation in these two phyla. In addition, the model accurately predicts the contribution of specific classes of MTs in chromosome segregation. Thus we present a model that offers a wider applicability to simulate the effects of perturbation of an event on the concerted process of the mitotic cell division.
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Affiliation(s)
- Sabyasachi Sutradhar
- Department of Solid State Physics, Indian Association for the Cultivation of Science, Kolkata 700032, India
| | - Vikas Yadav
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
| | - Shreyas Sridhar
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
| | - Lakshmi Sreekumar
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
| | - Dibyendu Bhattacharyya
- Tata Memorial Centre, Advanced Centre for Treatment Research and Education in Cancer, Kharghar, Navi Mumbai 410210, India
| | - Santanu Kumar Ghosh
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai, Mumbai 400076, India
| | - Raja Paul
- Department of Solid State Physics, Indian Association for the Cultivation of Science, Kolkata 700032, India
| | - Kaustuv Sanyal
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
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33
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Manck R, Ishitsuka Y, Herrero S, Takeshita N, Nienhaus GU, Fischer R. Genetic evidence for a microtubule-capture mechanism during polarised growth of Aspergillus nidulans. J Cell Sci 2015; 128:3569-82. [PMID: 26272919 DOI: 10.1242/jcs.169094] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 08/10/2015] [Indexed: 12/13/2022] Open
Abstract
The cellular switch from symmetry to polarity in eukaryotes depends on the microtubule (MT) and actin cytoskeletons. In fungi such as Schizosaccharomyces pombe or Aspergillus nidulans, the MT cytoskeleton determines the sites of actin polymerization through cortical cell-end marker proteins. Here we describe A. nidulans MT guidance protein A (MigA) as the first ortholog of the karyogamy protein Kar9 from Saccharomyces cerevisiae in filamentous fungi. A. nidulans MigA interacts with the cortical ApsA protein and is involved in spindle positioning during mitosis. MigA is also associated with septal and nuclear MT organizing centers (MTOCs). Super-resolution photoactivated localization microscopy (PALM) analyses revealed that MigA is recruited to assembling and retracting MT plus ends in an EbA-dependent manner. MigA is required for MT convergence in hyphal tips and plays a role in correct localization of the cell-end markers TeaA and TeaR. In addition, MigA interacts with a class-V myosin, suggesting that an active mechanism exists to capture MTs and to pull the ends along actin filaments. Hence, the organization of MTs and actin depend on each other, and positive feedback loops ensure robust polar growth.
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Affiliation(s)
- Raphael Manck
- Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Department of Microbiology, Hertzstrasse 16, Karlsruhe D-76187, Germany
| | - Yuji Ishitsuka
- Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Physics and Center for Functional Nanostructures, Karlsruhe 76131, Germany
| | - Saturnino Herrero
- Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Department of Microbiology, Hertzstrasse 16, Karlsruhe D-76187, Germany
| | - Norio Takeshita
- Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Department of Microbiology, Hertzstrasse 16, Karlsruhe D-76187, Germany University of Tsukuba, Faculty of Life and Environmental Sciences, Tsukuba, Ibaraki 305-8572, Japan
| | - G Ulrich Nienhaus
- Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Physics and Center for Functional Nanostructures, Karlsruhe 76131, Germany
| | - Reinhard Fischer
- Karlsruhe Institute of Technology (KIT) - South Campus, Institute for Applied Biosciences, Department of Microbiology, Hertzstrasse 16, Karlsruhe D-76187, Germany
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Abstract
The centrosome was discovered in the late 19th century when mitosis was first described. Long recognized as a key organelle of the spindle pole, its core component, the centriole, was realized more than 50 or so years later also to comprise the basal body of the cilium. Here, we chart the more recent acquisition of a molecular understanding of centrosome structure and function. The strategies for gaining such knowledge were quickly developed in the yeasts to decipher the structure and function of their distinctive spindle pole bodies. Only within the past decade have studies with model eukaryotes and cultured cells brought a similar degree of sophistication to our understanding of the centrosome duplication cycle and the multiple roles of this organelle and its component parts in cell division and signaling. Now as we begin to understand these functions in the context of development, the way is being opened up for studies of the roles of centrosomes in human disease.
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Affiliation(s)
- Jingyan Fu
- Cancer Research UK Cell Cycle Genetics Group, Department of Genetics, University of Cambridge, Cambridge CB2 3EH, United Kingdom
| | - Iain M Hagan
- Cancer Research UK Manchester Institute, University of Manchester, Withington, Manchester M20 4BX, United Kingdom
| | - David M Glover
- Cancer Research UK Cell Cycle Genetics Group, Department of Genetics, University of Cambridge, Cambridge CB2 3EH, United Kingdom
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35
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Gegg M, Böttcher A, Burtscher I, Hasenoeder S, Van Campenhout C, Aichler M, Walch A, Grant SGN, Lickert H. Flattop regulates basal body docking and positioning in mono- and multiciliated cells. eLife 2014; 3:e03842. [PMID: 25296022 PMCID: PMC4221739 DOI: 10.7554/elife.03842] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 10/07/2014] [Indexed: 12/29/2022] Open
Abstract
Planar cell polarity (PCP) regulates basal body (BB) docking and positioning during cilia formation, but the underlying mechanisms remain elusive. In this study, we investigate the uncharacterized gene Flattop (Fltp) that is transcriptionally activated during PCP acquisition in ciliated tissues. Fltp knock-out mice show BB docking and ciliogenesis defects in multiciliated lung cells. Furthermore, Fltp is necessary for kinocilium positioning in monociliated inner ear hair cells. In these cells, the core PCP molecule Dishevelled 2, the BB/spindle positioning protein Dlg3, and Fltp localize directly adjacent to the apical plasma membrane, physically interact and surround the BB at the interface of the microtubule and actin cytoskeleton. Dlg3 and Fltp knock-outs suggest that both cooperatively translate PCP cues for BB positioning in the inner ear. Taken together, the identification of novel BB/spindle positioning components as potential mediators of PCP signaling might have broader implications for other cell types, ciliary disease, and asymmetric cell division.
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Affiliation(s)
- Moritz Gegg
- Institute of Stem Cell Research, Helmholtz Center Munich, Munich, Germany
- Institute of Diabetes and Regeneration Research, Helmholtz Center Munich, Munich, Germany
| | - Anika Böttcher
- Institute of Stem Cell Research, Helmholtz Center Munich, Munich, Germany
- Institute of Diabetes and Regeneration Research, Helmholtz Center Munich, Munich, Germany
| | - Ingo Burtscher
- Institute of Stem Cell Research, Helmholtz Center Munich, Munich, Germany
- Institute of Diabetes and Regeneration Research, Helmholtz Center Munich, Munich, Germany
| | - Stefan Hasenoeder
- Institute of Stem Cell Research, Helmholtz Center Munich, Munich, Germany
- Institute of Diabetes and Regeneration Research, Helmholtz Center Munich, Munich, Germany
| | - Claude Van Campenhout
- Genetique du Developpement, L'Institut de biologie et de médecine moléculaires, Université libre de Bruxelles, Gosselies, Belgium
| | - Michaela Aichler
- Research Unit Analytical Pathology, Helmholtz Center Munich, Munich, Germany
| | - Axel Walch
- Research Unit Analytical Pathology, Helmholtz Center Munich, Munich, Germany
| | - Seth G N Grant
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
- Centre for Neuroregeneration, Univeristy of Edinburgh, Cambridge, United Kingdom
| | - Heiko Lickert
- Institute of Stem Cell Research, Helmholtz Center Munich, Munich, Germany
- Institute of Diabetes and Regeneration Research, Helmholtz Center Munich, Munich, Germany
- For correspondence:
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36
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López MP, Huber F, Grigoriev I, Steinmetz MO, Akhmanova A, Koenderink GH, Dogterom M. Actin-microtubule coordination at growing microtubule ends. Nat Commun 2014; 5:4778. [PMID: 25159196 PMCID: PMC4365169 DOI: 10.1038/ncomms5778] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 07/23/2014] [Indexed: 11/09/2022] Open
Abstract
To power dynamic processes in cells, the actin and microtubule cytoskeletons organize into complex structures. Although it is known that cytoskeletal coordination is vital for cell function, the mechanisms by which cross-linking proteins coordinate actin and microtubule activities remain poorly understood. In particular, it is unknown how the distinct mechanical properties of different actin architectures modulate the outcome of actin-microtubule interactions. To address this question, we engineered the protein TipAct, which links growing microtubule ends via end-binding proteins to actin filaments. We show that growing microtubules can be captured and guided by stiff actin bundles, leading to global actin-microtubule alignment. Conversely, growing microtubule ends can transport, stretch and bundle individual actin filaments, thereby globally defining actin filament organization. Our results provide a physical basis to understand actin-microtubule cross-talk, and reveal that a simple cross-linker can enable a mechanical feedback between actin and microtubule organization that is relevant to diverse biological contexts.
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Affiliation(s)
| | - Florian Huber
- FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
| | - Ilya Grigoriev
- Division of Cell Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Michel O. Steinmetz
- Laboratory of Biomolecular Research, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Anna Akhmanova
- Division of Cell Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | | | - Marileen Dogterom
- FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands
- Present address: Department of Bionanoscience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
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37
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Baumgärtner S, Tolić IM. Astral microtubule pivoting promotes their search for cortical anchor sites during mitosis in budding yeast. PLoS One 2014; 9:e93781. [PMID: 24721997 PMCID: PMC3983083 DOI: 10.1371/journal.pone.0093781] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 03/10/2014] [Indexed: 11/18/2022] Open
Abstract
Positioning of the mitotic spindle is crucial for proper cell division. In the budding yeast Saccharomyces cerevisiae, two mechanisms contribute to spindle positioning. In the Kar9 pathway, astral microtubules emanating from the daughter-bound spindle pole body interact via the linker protein Kar9 with the myosin Myo2, which moves the microtubule along the actin cables towards the neck. In the dynein pathway, astral microtubules off-load dynein onto the cortical anchor protein Num1, which is followed by dynein pulling on the spindle. Yet, the mechanism by which microtubules target cortical anchor sites is unknown. Here we quantify the pivoting motion of astral microtubules around the spindle pole bodies, which occurs during spindle translocation towards the neck and through the neck. We show that this pivoting is largely driven by the Kar9 pathway. The microtubules emanating from the daughter-bound spindle pole body pivot faster than those at the mother-bound spindle pole body. The Kar9 pathway reduces the time needed for an astral microtubule inside the daughter cell to start pulling on the spindle. Thus, we propose a new role for microtubule pivoting: By pivoting around the spindle pole body, microtubules explore the space laterally, which helps them search for cortical anchor sites in the context of spindle positioning in budding yeast.
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Affiliation(s)
- Stephan Baumgärtner
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Iva M. Tolić
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
- * E-mail:
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38
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Chen X, Shen J, Li X, Wang X, Long M, Lin F, Wei J, Yang L, Yang C, Dong K, Zhang H. Rlim, an E3 ubiquitin ligase, influences the stability of Stathmin protein in human osteosarcoma cells. Cell Signal 2014; 26:1532-8. [PMID: 24686088 DOI: 10.1016/j.cellsig.2014.03.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 03/14/2014] [Accepted: 03/14/2014] [Indexed: 12/21/2022]
Abstract
Stathmin is an oncoprotein and is expressed at high levels in a wide variety of human malignancies, which plays important roles in maintenance of malignant phenotypes. The regulation of Stathmin gene overexpression has been wildly explored, but the exact mechanism still needs to be elucidated. It is believed that regulation of an oncogene protein abundance through post-translational modifications is essential for maintenance of malignant phenotypes. Here we identified the Rlim, a Ring H2 zinc finger protein with intrinsic ubiquitin ligase activity, as a Stathmin-interacting protein that could increase Stathmin turnover through binding with this targeted protein and then induce its degradation by proteasome in a ubiquitin-dependent manner. Inhibition of endogenous Rlim expression by siRNA could increase the level of Stathmin protein, which further led to cell proliferation and cell cycle changes in human osteosarcoma cell lines. On the other hand, forced overexpression of Rlim could decrease the level of Stathmin protein. These results demonstrate that Rlim is involved in the negative regulation of Stathmin protein level through physical interaction and ubiquitin-mediated proteolysis. Hence, Rlim is a novel regulator of Stathmin protein in a ubiquitin-dependent manner, and represents a new pathway for malignant phenotype turnover by modulating the level of Stathmin protein in human osteosarcomas.
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Affiliation(s)
- Xi Chen
- Department of Medical Laboratory and Research Center, Tangdu Hospital, Fourth Military Medical University, Xi'an, China
| | - Jianjun Shen
- Department of Medical Laboratory and Research Center, Tangdu Hospital, Fourth Military Medical University, Xi'an, China
| | - Xingyu Li
- Department of Ophthalmology, Xi'an No. 4 Hospital, Xi'an, China
| | - Xi Wang
- Department of Medical Laboratory and Research Center, Tangdu Hospital, Fourth Military Medical University, Xi'an, China
| | - Min Long
- Department of Medical Laboratory and Research Center, Tangdu Hospital, Fourth Military Medical University, Xi'an, China
| | - Fang Lin
- Department of Medical Laboratory and Research Center, Tangdu Hospital, Fourth Military Medical University, Xi'an, China
| | - Junxia Wei
- Department of Medical Laboratory and Research Center, Tangdu Hospital, Fourth Military Medical University, Xi'an, China
| | - Longfei Yang
- Department of Medical Laboratory and Research Center, Tangdu Hospital, Fourth Military Medical University, Xi'an, China
| | - Chinglai Yang
- Department of Microbiology & Immunology, Emory University School of Medicine, Atlanta, USA
| | - Ke Dong
- Department of Medical Laboratory and Research Center, Tangdu Hospital, Fourth Military Medical University, Xi'an, China.
| | - Huizhong Zhang
- Department of Medical Laboratory and Research Center, Tangdu Hospital, Fourth Military Medical University, Xi'an, China.
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39
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Hamada T. Microtubule organization and microtubule-associated proteins in plant cells. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 312:1-52. [PMID: 25262237 DOI: 10.1016/b978-0-12-800178-3.00001-4] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Plants have unique microtubule (MT) arrays, cortical MTs, preprophase band, mitotic spindle, and phragmoplast, in the processes of evolution. These MT arrays control the directions of cell division and expansion especially in plants and are essential for plant morphogenesis and developments. Organizations and functions of these MT arrays are accomplished by diverse MT-associated proteins (MAPs). This review introduces 10 of conserved MAPs in eukaryote such as γ-TuC, augmin, katanin, kinesin, EB1, CLASP, MOR1/MAP215, MAP65, TPX2, formin, and several plant-specific MAPs such as CSI1, SPR2, MAP70, WVD2/WDL, RIP/MIDD, SPR1, MAP18/PCaP, EDE1, and MAP190. Most of the studies cited in this review have been analyzed in the particular model plant, Arabidopsis thaliana. The significant knowledge of A. thaliana is the important established base to understand MT organizations and functions in plants.
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Affiliation(s)
- Takahiro Hamada
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Tokyo, Japan.
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40
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Preciado López M, Huber F, Grigoriev I, Steinmetz MO, Akhmanova A, Dogterom M, Koenderink GH. In vitro reconstitution of dynamic microtubules interacting with actin filament networks. Methods Enzymol 2014; 540:301-20. [PMID: 24630114 DOI: 10.1016/b978-0-12-397924-7.00017-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Interactions between microtubules and actin filaments (F-actin) are essential for eukaryotic cell migration, polarization, growth, and division. Although the importance of these interactions has been long recognized, the inherent complexity of the cell interior hampers a detailed mechanistic study of how these two cytoskeletal systems influence each other. In this chapter, we show how in vitro reconstitution can be employed to study how actin filaments and dynamic microtubules affect each other's organization. While we focus here on the effect of steric interactions, these assays provide an ideal starting point to develop more complex studies through the addition of known F-actin-microtubule cross-linkers, or myosin II motors.
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Affiliation(s)
| | - Florian Huber
- FOM Institute AMOLF, Science Park, Amsterdam, The Netherlands
| | - Ilya Grigoriev
- Division of Cell Biology, Faculty of Science, Utrecht University, Padualaan, Utrecht, The Netherlands
| | - Michel O Steinmetz
- Laboratory of Biomolecular Research, Paul Scherrer Institut, Villigen, Switzerland
| | - Anna Akhmanova
- Division of Cell Biology, Faculty of Science, Utrecht University, Padualaan, Utrecht, The Netherlands
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Hazel J, Krutkramelis K, Mooney P, Tomschik M, Gerow K, Oakey J, Gatlin JC. Changes in cytoplasmic volume are sufficient to drive spindle scaling. Science 2013; 342:853-6. [PMID: 24233723 PMCID: PMC4004590 DOI: 10.1126/science.1243110] [Citation(s) in RCA: 147] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The mitotic spindle must function in cell types that vary greatly in size, and its dimensions scale with the rapid, reductive cell divisions that accompany early stages of development. The mechanism responsible for this scaling is unclear, because uncoupling cell size from a developmental or cellular context has proven experimentally challenging. We combined microfluidic technology with Xenopus egg extracts to characterize spindle assembly within discrete, geometrically defined volumes of cytoplasm. Reductions in cytoplasmic volume, rather than developmental cues or changes in cell shape, were sufficient to recapitulate spindle scaling observed in Xenopus embryos. Thus, mechanisms extrinsic to the spindle, specifically a limiting pool of cytoplasmic component(s), play a major role in determining spindle size.
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Affiliation(s)
- James Hazel
- Dept. of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | - Kaspars Krutkramelis
- Dept. of Chemical and Petroleum Engineering, University of Wyoming, Laramie, WY 82071, USA
| | - Paul Mooney
- Dept. of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | - Miroslav Tomschik
- Dept. of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | - Ken Gerow
- Dept. of Statistics, University of Wyoming, Laramie, WY 82071, USA
| | - John Oakey
- Dept. of Chemical and Petroleum Engineering, University of Wyoming, Laramie, WY 82071, USA
| | - J. C. Gatlin
- Dept. of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
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Akhshi TK, Wernike D, Piekny A. Microtubules and actin crosstalk in cell migration and division. Cytoskeleton (Hoboken) 2013; 71:1-23. [DOI: 10.1002/cm.21150] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 10/02/2013] [Accepted: 10/06/2013] [Indexed: 12/22/2022]
Affiliation(s)
| | - Denise Wernike
- Department of Biology; Concordia University; Montreal Quebec Canada
| | - Alisa Piekny
- Department of Biology; Concordia University; Montreal Quebec Canada
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43
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Nazarova E, O'Toole E, Kaitna S, Francois P, Winey M, Vogel J. Distinct roles for antiparallel microtubule pairing and overlap during early spindle assembly. Mol Biol Cell 2013; 24:3238-50. [PMID: 23966467 PMCID: PMC3806661 DOI: 10.1091/mbc.e13-05-0232] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
During spindle assembly, microtubules may attach to kinetochores or pair to form antiparallel pairs or interpolar microtubules, which span the two spindle poles and contribute to mitotic pole separation and chromosome segregation. Events in the specification of the interpolar microtubules are poorly understood. Using three-dimensional electron tomography and analysis of spindle dynamical behavior in living cells, we investigated the process of spindle assembly. Unexpectedly, we found that the phosphorylation state of an evolutionarily conserved Cdk1 site (S360) in γ-tubulin is correlated with the number and organization of interpolar microtubules. Mimicking S360 phosphorylation (S360D) results in bipolar spindles with a normal number of microtubules but lacking interpolar microtubules. Inhibiting S360 phosphorylation (S360A) results in spindles with interpolar microtubules and high-angle, antiparallel microtubule pairs. The latter are also detected in wild-type spindles <1 μm in length, suggesting that high-angle microtubule pairing represents an intermediate step in interpolar microtubule formation. Correlation of spindle architecture with dynamical behavior suggests that microtubule pairing is sufficient to separate the spindle poles, whereas interpolar microtubules maintain the velocity of pole displacement during early spindle assembly. Our findings suggest that the number of interpolar microtubules formed during spindle assembly is controlled in part through activities at the spindle poles.
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Affiliation(s)
- Elena Nazarova
- Department of Biology, McGill University, Montreal, QC H3G 0B1, Canada Department of Physics, McGill University, Montreal, QC H3G 0B1, Canada Molecular, Cellular and Developmental Biology, University of Colorado at Boulder, Boulder CO 80309
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Ferreira JG, Pereira AJ, Akhmanova A, Maiato H. Aurora B spatially regulates EB3 phosphorylation to coordinate daughter cell adhesion with cytokinesis. ACTA ACUST UNITED AC 2013; 201:709-24. [PMID: 23712260 PMCID: PMC3664705 DOI: 10.1083/jcb.201301131] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
During mitosis, human cells round up, decreasing their adhesion to extracellular substrates. This must be quickly reestablished by poorly understood cytoskeleton remodeling mechanisms that prevent detachment from epithelia, while ensuring the successful completion of cytokinesis. Here we show that the microtubule end-binding (EB) proteins EB1 and EB3 play temporally distinct roles throughout cell division. Whereas EB1 was involved in spindle orientation before anaphase, EB3 was required for stabilization of focal adhesions and coordinated daughter cell spreading during mitotic exit. Additionally, EB3 promoted midbody microtubule stability and, consequently, midbody stabilization necessary for efficient cytokinesis. Importantly, daughter cell adhesion and cytokinesis completion were spatially regulated by distinct states of EB3 phosphorylation on serine 176 by Aurora B. This EB3 phosphorylation was enriched at the midbody and shown to control cortical microtubule growth. These findings uncover differential roles of EB proteins and explain the importance of an Aurora B phosphorylation gradient for the spatiotemporal regulation of microtubule function during mitotic exit and cytokinesis.
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Affiliation(s)
- Jorge G Ferreira
- Chromosome Instability and Dynamics Laboratory, Instituto de Biologia Molecular e Celular (IBMC), University of Porto, Porto, Portugal
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45
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Cane S, Ye AA, Luks-Morgan SJ, Maresca TJ. Elevated polar ejection forces stabilize kinetochore-microtubule attachments. ACTA ACUST UNITED AC 2013; 200:203-18. [PMID: 23337118 PMCID: PMC3549975 DOI: 10.1083/jcb.201211119] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Polar ejection forces, which push chromosomes away from spindle poles, modulate kinetochore–microtubule attachment stability. Chromosome biorientation promotes congression and generates tension that stabilizes kinetochore–microtubule (kt-MT) interactions. Forces produced by molecular motors also contribute to chromosome alignment, but their impact on kt-MT attachment stability is unclear. A critical force that acts on chromosomes is the kinesin-10–dependent polar ejection force (PEF). PEFs are proposed to facilitate congression by pushing chromosomes away from spindle poles, although knowledge of the molecular mechanisms underpinning PEF generation is incomplete. Here, we describe a live-cell PEF assay in which tension was applied to chromosomes by manipulating levels of the chromokinesin NOD (no distributive disjunction; Drosophila melanogaster kinesin-10). NOD stabilized syntelic kt-MT attachments in a dose- and motor-dependent manner by overwhelming the ability of Aurora B to mediate error correction. NOD-coated chromatin stretched away from the pole via lateral and end-on interactions with microtubules, and NOD chimeras with either plus end–directed motility or tip-tracking activity produced PEFs. Thus, kt-MT attachment stability is modulated by PEFs, which can be generated by distinct force-producing interactions between chromosomes and dynamic spindle microtubules.
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Affiliation(s)
- Stuart Cane
- Biology Department, University of Massachusetts, Amherst, MA 01003, USA
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Abstract
Accurate positioning of spindles is essential for asymmetric mitotic and meiotic cell divisions that are crucial for animal development and oocyte maturation, respectively. The predominant model for spindle positioning, termed "cortical pulling," involves attachment of the microtubule-based motor cytoplasmic dynein to the cortex, where it exerts a pulling force on microtubules that extend from the spindle poles to the cell cortex, thereby displacing the spindle. Recent studies have addressed important details of the cortical pulling mechanism and have revealed alternative mechanisms that may be used when microtubules do not extend from the spindle to the cortex.
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Affiliation(s)
- Francis J McNally
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA.
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Alonso A, D'Silva S, Rahman M, Meluh PB, Keeling J, Meednu N, Hoops HJ, Miller RK. The yeast homologue of the microtubule-associated protein Lis1 interacts with the sumoylation machinery and a SUMO-targeted ubiquitin ligase. Mol Biol Cell 2012; 23:4552-66. [PMID: 23034179 PMCID: PMC3510017 DOI: 10.1091/mbc.e12-03-0195] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The two yeast members of the CLIP-170/Bik1p and Lis1/Pac1p families of microtubule-associated proteins are shown to interact with the sumoylation machinery and the STUbL complex Ris1p–Nis1p. Pac1p can be modified by both SUMO and ubiquitin. The She1 regulator of dynactin is identified as a novel inhibitor of Pac1p modification. Microtubules and microtubule-associated proteins are fundamental for multiple cellular processes, including mitosis and intracellular motility, but the factors that control microtubule-associated proteins (MAPs) are poorly understood. Here we show that two MAPs—the CLIP-170 homologue Bik1p and the Lis1 homologue Pac1p—interact with several proteins in the sumoylation pathway. Bik1p and Pac1p interact with Smt3p, the yeast SUMO; Ubc9p, an E2; and Nfi1p, an E3. Bik1p interacts directly with SUMO in vitro, and overexpression of Smt3p and Bik1p results in its in vivo sumoylation. Modified Pac1p is observed when the SUMO protease Ulp1p is inactivated. Both ubiquitin and Smt3p copurify with Pac1p. In contrast to ubiquitination, sumoylation does not directly tag the substrate for degradation. However, SUMO-targeted ubiquitin ligases (STUbLs) can recognize a sumoylated substrate and promote its degradation via ubiquitination and the proteasome. Both Pac1p and Bik1p interact with the STUbL Nis1p-Ris1p and the protease Wss1p. Strains deleted for RIS1 or WSS1 accumulate Pac1p conjugates. This suggests a novel model in which the abundance of these MAPs may be regulated via STUbLs. Pac1p modification is also altered by Kar9p and the dynein regulator She1p. This work has implications for the regulation of dynein's interaction with various cargoes, including its off-loading to the cortex.
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Affiliation(s)
- Annabel Alonso
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA
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48
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Hotz M, Lengefeld J, Barral Y. The MEN mediates the effects of the spindle assembly checkpoint on Kar9-dependent spindle pole body inheritance in budding yeast. Cell Cycle 2012; 11:3109-16. [PMID: 22871738 DOI: 10.4161/cc.21504] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Many asymmetrically dividing cells segregate the poles of the mitotic spindle non-randomly between their two daughters. In budding yeast, the protein Kar9 localizes almost exclusively to the astral microtubules emanating from the old spindle pole body (SPB) and promotes its movement toward the bud. Thereby, Kar9 orients the spindle relative to the division axis. Here, we show that beyond perturbing Kar9 distribution, activation of the spindle assembly checkpoint (SAC) randomizes SPB inheritance. Inactivation of the B-type cyclin Clb5 led to a SAC-dependent defect in Kar9 orientation and SPB segregation. Furthermore, unlike the Clb4-dependent pathway, the Clb5- and SAC-dependent pathways functioned genetically upstream of the mitotic exit network (MEN) in SPB specification and Kar9-dependent SPB inheritance. Together, our study indicates that Clb5 functions in spindle assembly and that the SAC controls the specification and inheritance of yeast SPBs through inhibition of the MEN.
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Affiliation(s)
- Manuel Hotz
- Institute of Biochemistry, Biology Department, ETH Zurich, Zurich, Switzerland
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Abstract
The Saccharomyces cerevisiae mitotic spindle in budding yeast is exemplified by its simplicity and elegance. Microtubules are nucleated from a crystalline array of proteins organized in the nuclear envelope, known as the spindle pole body in yeast (analogous to the centrosome in larger eukaryotes). The spindle has two classes of nuclear microtubules: kinetochore microtubules and interpolar microtubules. One kinetochore microtubule attaches to a single centromere on each chromosome, while approximately four interpolar microtubules emanate from each pole and interdigitate with interpolar microtubules from the opposite spindle to provide stability to the bipolar spindle. On the cytoplasmic face, two to three microtubules extend from the spindle pole toward the cell cortex. Processes requiring microtubule function are limited to spindles in mitosis and to spindle orientation and nuclear positioning in the cytoplasm. Microtubule function is regulated in large part via products of the 6 kinesin gene family and the 1 cytoplasmic dynein gene. A single bipolar kinesin (Cin8, class Kin-5), together with a depolymerase (Kip3, class Kin-8) or minus-end-directed kinesin (Kar3, class Kin-14), can support spindle function and cell viability. The remarkable feature of yeast cells is that they can survive with microtubules and genes for just two motor proteins, thus providing an unparalleled system to dissect microtubule and motor function within the spindle machine.
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50
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SPOC alert—When chromosomes get the wrong direction. Exp Cell Res 2012; 318:1421-7. [DOI: 10.1016/j.yexcr.2012.03.031] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 03/28/2012] [Accepted: 03/29/2012] [Indexed: 12/16/2022]
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