1
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Meier SM, Steinmetz MO, Barral Y. Microtubule specialization by +TIP networks: from mechanisms to functional implications. Trends Biochem Sci 2024; 49:318-332. [PMID: 38350804 DOI: 10.1016/j.tibs.2024.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 12/23/2023] [Accepted: 01/12/2024] [Indexed: 02/15/2024]
Abstract
To fulfill their actual cellular role, individual microtubules become functionally specialized through a broad range of mechanisms. The 'search and capture' model posits that microtubule dynamics and functions are specified by cellular targets that they capture (i.e., a posteriori), independently of the microtubule-organizing center (MTOC) they emerge from. However, work in budding yeast indicates that MTOCs may impart a functional identity to the microtubules they nucleate, a priori. Key effectors in this process are microtubule plus-end tracking proteins (+TIPs), which track microtubule tips to regulate their dynamics and facilitate their targeted interactions. In this review, we discuss potential mechanisms of a priori microtubule specialization, focusing on recent findings indicating that +TIP networks may undergo liquid biomolecular condensation in different cell types.
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Affiliation(s)
- Sandro M Meier
- Institute of Biochemistry, Department of Biology, and Bringing Materials to Life Initiative, ETH Zürich, Switzerland; Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, Villigen, Switzerland; Bringing Materials to Life Initiative, ETH Zürich, Switzerland
| | - Michel O Steinmetz
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, Villigen, Switzerland; University of Basel, Biozentrum, CH-4056 Basel, Switzerland.
| | - Yves Barral
- Institute of Biochemistry, Department of Biology, and Bringing Materials to Life Initiative, ETH Zürich, Switzerland; Bringing Materials to Life Initiative, ETH Zürich, Switzerland.
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2
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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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3
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Ekal L, Alqahtani AMS, Schuldiner M, Zalckvar E, Hettema EH, Ayscough KR. Spindle Position Checkpoint Kinase Kin4 Regulates Organelle Transport in Saccharomyces cerevisiae. Biomolecules 2023; 13:1098. [PMID: 37509134 PMCID: PMC10377308 DOI: 10.3390/biom13071098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 06/29/2023] [Accepted: 07/04/2023] [Indexed: 07/30/2023] Open
Abstract
Membrane-bound organelles play important, frequently essential, roles in cellular metabolism in eukaryotes. Hence, cells have evolved molecular mechanisms to closely monitor organelle dynamics and maintenance. The actin cytoskeleton plays a vital role in organelle transport and positioning across all eukaryotes. Studies in the budding yeast Saccharomyces cerevisiae (S. cerevisiae) revealed that a block in actomyosin-dependent transport affects organelle inheritance to daughter cells. Indeed, class V Myosins, Myo2, and Myo4, and many of their organelle receptors, have been identified as key factors in organelle inheritance. However, the spatiotemporal regulation of yeast organelle transport remains poorly understood. Using peroxisome inheritance as a proxy to study actomyosin-based organelle transport, we performed an automated genome-wide genetic screen in S. cerevisiae. We report that the spindle position checkpoint (SPOC) kinase Kin4 and, to a lesser extent, its paralog Frk1, regulates peroxisome transport, independent of their role in the SPOC. We show that Kin4 requires its kinase activity to function and that both Kin4 and Frk1 protect Inp2, the peroxisomal Myo2 receptor, from degradation in mother cells. In addition, vacuole inheritance is also affected in kin4/frk1-deficient cells, suggesting a common regulatory mechanism for actin-based transport for these two organelles in yeast. More broadly our findings have implications for understanding actomyosin-based transport in cells.
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Affiliation(s)
- Lakhan Ekal
- School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Abdulaziz M S Alqahtani
- School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
- Department of Biology, Faculty of Science, University of Bisha, P.O. Box 551, Bisha 61922, Saudi Arabia
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Einat Zalckvar
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ewald H Hettema
- School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
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4
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Meier SM, Farcas AM, Kumar A, Ijavi M, Bill RT, Stelling J, Dufresne ER, Steinmetz MO, Barral Y. Multivalency ensures persistence of a +TIP body at specialized microtubule ends. Nat Cell Biol 2023; 25:56-67. [PMID: 36536177 PMCID: PMC9859758 DOI: 10.1038/s41556-022-01035-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 10/21/2022] [Indexed: 12/24/2022]
Abstract
Microtubule plus-end tracking proteins (+TIPs) control microtubule specialization and are as such essential for cell division and morphogenesis. Here we investigated interactions and functions of the budding yeast Kar9 network consisting of the core +TIP proteins Kar9 (functional homologue of APC, MACF and SLAIN), Bim1 (orthologous to EB1) and Bik1 (orthologous to CLIP-170). A multivalent web of redundant interactions links the three +TIPs together to form a '+TIP body' at the end of chosen microtubules. This body behaves as a liquid condensate that allows it to persist on both growing and shrinking microtubule ends, and to function as a mechanical coupling device between microtubules and actin cables. Our study identifies nanometre-scale condensates as effective cellular structures and underlines the power of dissecting the web of low-affinity interactions driving liquid-liquid phase separation in order to establish how condensation processes support cell function.
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Affiliation(s)
- Sandro M Meier
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, Villigen, Switzerland.,Department of Biology, Institute of Biochemistry, ETH Zürich, Zürich, Switzerland.,Bringing Materials to Life Initiative, ETH Zürich, Zürich, Switzerland
| | - Ana-Maria Farcas
- Department of Biology, Institute of Biochemistry, ETH Zürich, Zürich, Switzerland.,Bringing Materials to Life Initiative, ETH Zürich, Zürich, Switzerland
| | - Anil Kumar
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, Villigen, Switzerland.,ImmunOs Therapeutics AG, Schlieren, Switzerland
| | - Mahdiye Ijavi
- Bringing Materials to Life Initiative, ETH Zürich, Zürich, Switzerland.,Department of Materials, ETH Zürich, Zürich, Switzerland
| | - Robert T Bill
- Department of Biology, Institute of Biochemistry, ETH Zürich, Zürich, Switzerland.,Department of Molecular Life Sciences, University of Zürich, Zürich, Switzerland
| | - Jörg Stelling
- Department of Biosystems Science and Engineering and SIB Swiss Institute of Bioinformatics, ETH Zürich, Basel, Switzerland
| | - Eric R Dufresne
- Bringing Materials to Life Initiative, ETH Zürich, Zürich, Switzerland.,Department of Materials, ETH Zürich, Zürich, Switzerland
| | - Michel O Steinmetz
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, Villigen, Switzerland. .,University of Basel, Biozentrum, Basel, Switzerland.
| | - Yves Barral
- Department of Biology, Institute of Biochemistry, ETH Zürich, Zürich, Switzerland. .,Bringing Materials to Life Initiative, ETH Zürich, Zürich, Switzerland.
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5
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Liu Y, Li L, Yu C, Zeng F, Niu F, Wei Z. Cargo Recognition Mechanisms of Yeast Myo2 Revealed by AlphaFold2-Powered Protein Complex Prediction. Biomolecules 2022; 12:biom12081032. [PMID: 35892342 PMCID: PMC9330073 DOI: 10.3390/biom12081032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/17/2022] [Accepted: 07/20/2022] [Indexed: 02/01/2023] Open
Abstract
Myo2, a yeast class V myosin, transports a broad range of organelles and plays important roles in various cellular processes, including cell division in budding yeast. Despite the fact that several structures of Myo2/cargo adaptor complexes have been determined, the understanding of the versatile cargo-binding modes of Myo2 is still very limited, given the large number of cargo adaptors identified for Myo2. Here, we used ColabFold, an AlphaFold2-powered and easy-to-use tool, to predict the complex structures of Myo2-GTD and its several cargo adaptors. After benchmarking the prediction strategy with three Myo2/cargo adaptor complexes that have been determined previously, we successfully predicted the atomic structures of Myo2-GTD in complex with another three cargo adaptors, Vac17, Kar9 and Pea2, which were confirmed by our biochemical characterizations. By systematically comparing the interaction details of the six complexes of Myo2 and its cargo adaptors, we summarized the cargo-binding modes on the three conserved sites of Myo2-GTD, providing an overall picture of the versatile cargo-recognition mechanisms of Myo2. In addition, our study demonstrates an efficient and effective solution to study protein-protein interactions in the future via the AlphaFold2-powered prediction.
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Affiliation(s)
- Yong Liu
- SUSTech-HIT Joint PhD Program, Harbin Institute of Technology, Harbin 150001, China;
- Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China; (L.L.); (C.Y.); (F.Z.)
- Brain Research Center, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Lingxuan Li
- Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China; (L.L.); (C.Y.); (F.Z.)
- Brain Research Center, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Cong Yu
- Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China; (L.L.); (C.Y.); (F.Z.)
- Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research, Southern University of Science and Technology, Shenzhen 518055, China
- Shenzhen Key Laboratory of Cell Microenvironment, Southern University of Science and Technology, Shenzhen 518055, China
| | - Fuxing Zeng
- Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China; (L.L.); (C.Y.); (F.Z.)
| | - Fengfeng Niu
- Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China; (L.L.); (C.Y.); (F.Z.)
- Brain Research Center, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
- Correspondence: (F.N.); (Z.W.)
| | - Zhiyi Wei
- Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China; (L.L.); (C.Y.); (F.Z.)
- Brain Research Center, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
- Correspondence: (F.N.); (Z.W.)
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6
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Dang H, Martin‐Villalba A, Schiebel E. Centrosome linker protein C-Nap1 maintains stem cells in mouse testes. EMBO Rep 2022; 23:e53805. [PMID: 35599622 PMCID: PMC9253759 DOI: 10.15252/embr.202153805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 04/13/2022] [Accepted: 04/27/2022] [Indexed: 11/27/2022] Open
Abstract
The centrosome linker component C-Nap1 (encoded by CEP250) anchors filaments to centrioles that provide centrosome cohesion by connecting the two centrosomes of an interphase cell into a single microtubule organizing unit. The role of the centrosome linker during development of an animal remains enigmatic. Here, we show that male CEP250-/- mice are sterile because sperm production is abolished. Premature centrosome separation means that germ stem cells in CEP250-/- mice fail to establish an E-cadherin polarity mark and are unable to maintain the older mother centrosome on the basal site of the seminiferous tubules. This failure prompts premature stem cell differentiation in expense of germ stem cell expansion. The concomitant induction of apoptosis triggers the complete depletion of germ stem cells and consequently infertility. Our study reveals a role for centrosome cohesion in asymmetric cell division, stem cell maintenance, and fertility.
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Affiliation(s)
- Hairuo Dang
- Zentrum für Molekulare Biologie der Universität HeidelbergDeutsches Krebsforschungszentrum‐ZMBH AllianzUniversität HeidelbergHeidelbergGermany
- Heidelberg Biosciences International Graduate School (HBIGS)Universität HeidelbergHeidelbergGermany
| | - Ana Martin‐Villalba
- Deutsches Krebsforschungszentrum‐ZMBH AllianzUniversität HeidelbergHeidelbergGermany
| | - Elmar Schiebel
- Zentrum für Molekulare Biologie der Universität HeidelbergDeutsches Krebsforschungszentrum‐ZMBH AllianzUniversität HeidelbergHeidelbergGermany
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7
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Cross-linkers at growing microtubule ends generate forces that drive actin transport. Proc Natl Acad Sci U S A 2022; 119:e2112799119. [PMID: 35271394 PMCID: PMC8931237 DOI: 10.1073/pnas.2112799119] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Complex cellular processes such as cell migration require coordinated remodeling of both the actin and the microtubule cytoskeleton. The two networks for instance exert forces on each other via active motor proteins. Here we show that, surprisingly, coupling via passive cross-linkers can also result in force generation. We specifically study the transport of actin filaments by growing microtubule ends. We show by cell-free reconstitution experiments, computer simulations, and theoretical modeling that this transport is driven by the affinity of the cross-linker for the chemically distinct microtubule tip region. Our work predicts that growing microtubules could potentially rapidly relocate newly nucleated actin filaments to the leading edge of the cell and thus boost migration. The actin and microtubule cytoskeletons form active networks in the cell that can contract and remodel, resulting in vital cellular processes such as cell division and motility. Motor proteins play an important role in generating the forces required for these processes, but more recently the concept of passive cross-linkers being able to generate forces has emerged. So far, these passive cross-linkers have been studied in the context of separate actin and microtubule systems. Here, we show that cross-linkers also allow actin and microtubules to exert forces on each other. More specifically, we study single actin filaments that are cross-linked to growing microtubule ends, using in vitro reconstitution, computer simulations, and a minimal theoretical model. We show that microtubules can transport actin filaments over large (micrometer-range) distances and find that this transport results from two antagonistic forces arising from the binding of cross-linkers to the overlap between the actin and microtubule filaments. The cross-linkers attempt to maximize the overlap between the actin and the tip of the growing microtubules, creating an affinity-driven forward condensation force, and simultaneously create a competing friction force along the microtubule lattice. We predict and verify experimentally how the average transport time depends on the actin filament length and the microtubule growth velocity, confirming the competition between a forward condensation force and a backward friction force. In addition, we theoretically predict and experimentally verify that the condensation force is of the order of 0.1 pN. Thus, our results reveal an active mechanism for local actin remodeling by growing microtubules that relies on passive cross-linkers.
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8
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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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9
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Li KW, Lu MS, Iwamoto Y, Drubin DG, Pedersen RTA. A preferred sequence for organelle inheritance during polarized cell growth. J Cell Sci 2021; 134:272417. [PMID: 34622919 PMCID: PMC8627559 DOI: 10.1242/jcs.258856] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 09/27/2021] [Indexed: 12/25/2022] Open
Abstract
Some organelles cannot be synthesized anew, so they are segregated into daughter cells during cell division. In Saccharomyces cerevisiae, daughter cells bud from mother cells and are populated by organelles inherited from the mothers. To determine whether this organelle inheritance occurs in a stereotyped manner, we tracked organelles using fluorescence microscopy. We describe a program for organelle inheritance in budding yeast. The cortical endoplasmic reticulum (ER) and peroxisomes are inherited concomitantly with bud emergence. Next, vacuoles are inherited in small buds, followed closely by mitochondria. Finally, the nucleus and perinuclear ER are inherited when buds have nearly reached their maximal size. Because organelle inheritance timing correlates with bud morphology, which is coupled to the cell cycle, we tested whether disrupting the cell cycle alters organelle inheritance order. By arresting cell cycle progression but allowing continued bud growth, we determined that organelle inheritance still occurs when DNA replication is blocked, and that the general inheritance order is maintained. Thus, organelle inheritance follows a preferred order during polarized cell division and does not require completion of S-phase. Summary: Organelles are interconnected by contact sites, but they must be inherited from mother cells into buds during budding yeast mitosis. We report that this process occurs in a preferred sequence.
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Affiliation(s)
- Kathryn W Li
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Michelle S Lu
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Yuichiro Iwamoto
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - David G Drubin
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Ross T A Pedersen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
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10
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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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11
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Structure and regulation of the microtubule plus-end tracking protein Kar9. Structure 2021; 29:1266-1278.e4. [PMID: 34237274 DOI: 10.1016/j.str.2021.06.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 04/26/2021] [Accepted: 06/14/2021] [Indexed: 11/22/2022]
Abstract
In many eukaryotes, coordination of chromosome segregation with cell cleavage relies on the patterned interaction of specific microtubules with actin filaments through dedicated microtubule plus-end tracking proteins (+TIPs). However, how these +TIPs are spatially controlled is unclear. The yeast +TIP Kar9 drives one of the spindle aster microtubules along actin cables to align the mitotic spindle with the axis of cell division. Here, we report the crystal structure of Kar9's folded domain, revealing spectrin repeats reminiscent of the +TIPs MACF/ACF7/Shot and PRC1/Ase1. Point mutations abrogating spectrin-repeat-mediated dimerization of Kar9 reduced and randomized Kar9 distribution to microtubule tips, and impaired spindle positioning. Six Cdk1 sites surround the Kar9 dimerization interface. Their phosphomimetic substitution inhibited Kar9 dimerization, displaced Kar9 from microtubules, and affected its interaction with the myosin motor Myo2. Our results provide molecular-level understanding on how diverse cell types may regulate and pattern microtubule-actin interactions to orchestrate their divisions.
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12
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Gihana GM, Cross-Najafi AA, Lacefield S. The mitotic exit network regulates the spatiotemporal activity of Cdc42 to maintain cell size. J Cell Biol 2021; 220:211575. [PMID: 33284320 PMCID: PMC7721911 DOI: 10.1083/jcb.202001016] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 09/29/2020] [Accepted: 10/29/2020] [Indexed: 12/29/2022] Open
Abstract
During G1 in budding yeast, the Cdc42 GTPase establishes a polar front, along which actin is recruited to direct secretion for bud formation. Cdc42 localizes at the bud cortex and then redistributes between mother and daughter in anaphase. The molecular mechanisms that terminate Cdc42 bud-localized activity during mitosis are poorly understood. We demonstrate that the activity of the Cdc14 phosphatase, released through the mitotic exit network, is required for Cdc42 redistribution between mother and bud. Induced Cdc14 nucleolar release results in premature Cdc42 redistribution between mother and bud. Inhibition of Cdc14 causes persistence of Cdc42 bud localization, which perturbs normal cell size and spindle positioning. Bem3, a Cdc42 GAP, binds Cdc14 and is dephosphorylated at late anaphase in a Cdc14-dependent manner. We propose that Cdc14 dephosphorylates and activates Bem3 to allow Cdc42 inactivation and redistribution. Our results uncover a mechanism through which Cdc14 regulates the spatiotemporal activity of Cdc42 to maintain normal cell size at cytokinesis.
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Affiliation(s)
| | | | - Soni Lacefield
- Department of Biology, Indiana University, Bloomington, IN
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13
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Meziane M, Genthial R, Vogel J. Kar9 symmetry breaking alone is insufficient to ensure spindle alignment. Sci Rep 2021; 11:4227. [PMID: 33608583 PMCID: PMC7895971 DOI: 10.1038/s41598-021-83136-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 01/28/2021] [Indexed: 11/18/2022] Open
Abstract
Spindle positioning must be tightly regulated to ensure asymmetric cell divisions are successful. In budding yeast, spindle positioning is mediated by the asymmetric localization of microtubule + end tracking protein Kar9. Kar9 asymmetry is believed to be essential for spindle alignment. However, the temporal correlation between symmetry breaking and spindle alignment has not been measured. Here, we establish a method of quantifying Kar9 symmetry breaking and find that Kar9 asymmetry is not well coupled with stable spindle alignment. We report the spindles are not aligned in the majority of asymmetric cells. Rather, stable alignment is correlated with Kar9 residence in the bud, regardless of symmetry state. Our findings suggest that Kar9 asymmetry alone is insufficient for stable alignment and reveal a possible role for Swe1 in regulating Kar9 residence in the bud.
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Affiliation(s)
- Miram Meziane
- Department of Biology, McGill University, Montreal, QC, H3G 0B1, Canada
| | - Rachel Genthial
- Department of Biology, McGill University, Montreal, QC, H3G 0B1, Canada
| | - Jackie Vogel
- Department of Biology, McGill University, Montreal, QC, H3G 0B1, Canada.
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14
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Wong S, Weisman LS. Roles and regulation of myosin V interaction with cargo. Adv Biol Regul 2021; 79:100787. [PMID: 33541831 PMCID: PMC7920922 DOI: 10.1016/j.jbior.2021.100787] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 01/11/2021] [Indexed: 05/08/2023]
Abstract
A major question in cell biology is, how are organelles and large macromolecular complexes transported within a cell? Myosin V molecular motors play critical roles in the distribution of organelles, vesicles, and mRNA. Mis-localization of organelles that depend on myosin V motors underlie diseases in the skin, gut, and brain. Thus, the delivery of organelles to their proper destination is important for animal physiology and cellular function. Cargoes attach to myosin V motors via cargo specific adaptor proteins, which transiently bridge motors to their cargoes. Regulation of these adaptor proteins play key roles in the regulation of cargo transport. Emerging studies reveal that cargo adaptors play additional essential roles in the activation of myosin V, and the regulation of actin filaments. Here, we review how motor-adaptor interactions are controlled to regulate the proper loading and unloading of cargoes, as well as roles of adaptor proteins in the regulation of myosin V activity and the dynamics of actin filaments.
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Affiliation(s)
- Sara Wong
- Cell and Molecular Biology, University of Michigan, Ann Arbor, United States; Life Sciences Institute, University of Michigan, Ann Arbor, United States
| | - Lois S Weisman
- Cell and Developmental Biology, University of Michigan, Ann Arbor, United States; Life Sciences Institute, University of Michigan, Ann Arbor, United States.
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15
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Matellán L, Manzano-López J, Monje-Casas F. Polo-like kinase acts as a molecular timer that safeguards the asymmetric fate of spindle microtubule-organizing centers. eLife 2020; 9:61488. [PMID: 33135999 PMCID: PMC7669271 DOI: 10.7554/elife.61488] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 10/20/2020] [Indexed: 12/27/2022] Open
Abstract
The microtubules that form the mitotic spindle originate from microtubule-organizing centers (MTOCs) located at either pole. After duplication, spindle MTOCs can be differentially inherited during asymmetric cell division in organisms ranging from yeast to humans. Problems with establishing predetermined spindle MTOC inheritance patterns during stem cell division have been associated with accelerated cellular aging and the development of both cancer and neurodegenerative disorders. Here, we expand the repertoire of functions Polo-like kinase family members fulfill in regulating pivotal cell cycle processes. We demonstrate that the Plk1 homolog Cdc5 acts as a molecular timer that facilitates the timely and sequential recruitment of two key determinants of spindle MTOCs distribution, that is the γ-tubulin complex receptor Spc72 and the protein Kar9, and establishes the fate of these structures, safeguarding their asymmetric inheritance during Saccharomyces cerevisiae mitosis.
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Affiliation(s)
- Laura Matellán
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER) / Spanish National Research Council (CSIC) - University of Seville - University Pablo de Olavide, Sevilla, Spain
| | - Javier Manzano-López
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER) / Spanish National Research Council (CSIC) - University of Seville - University Pablo de Olavide, Sevilla, Spain
| | - Fernando Monje-Casas
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER) / Spanish National Research Council (CSIC) - University of Seville - University Pablo de Olavide, Sevilla, Spain
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16
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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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17
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Renshaw H, Juvvadi PR, Cole DC, Steinbach WJ. The class V myosin interactome of the human pathogen Aspergillus fumigatus reveals novel interactions with COPII vesicle transport proteins. Biochem Biophys Res Commun 2020; 527:232-237. [PMID: 32446373 PMCID: PMC7248123 DOI: 10.1016/j.bbrc.2020.04.111] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 04/21/2020] [Indexed: 11/21/2022]
Abstract
The human fungal pathogen Aspergillus fumigatus causes life-threatening invasive aspergillosis in immunocompromised individuals. Adaptation to the host environment is integral to survival of A. fumigatus and requires the coordination of short- and long-distance vesicular transport to move essential components throughout the fungus. We previously reported the importance of MyoE, the only class V myosin, for hyphal growth and virulence of A. fumigatus. Class V myosins are actin-based, cargo-carrying motor proteins that contain unique binding sites for specific cargo. Specific cargo carried by myosin V has not been identified in any fungus, and previous studies have only identified single components that interact with class V myosins. Here we utilized a mass spectrometry-based whole proteomic approach to identify MyoE interacting proteins in A. fumigatus for the first time. Several proteins previously shown to interact with myosin V through physical and genetic approaches were confirmed, validating our proteomic analysis. Importantly, we identified novel MyoE-interacting proteins, including members of the cytoskeleton network, cell wall synthesis, calcium signaling and a group of coat protein complex II (COPII) proteins involved in the endoplasmic reticulum (ER) to Golgi transport. Furthermore, we analyzed the localization patterns of the COPII proteins, UsoA (Uso1), SrgE (Sec31), and SrgF (Sec23), which suggested a potential role for MyoE in ER to Golgi trafficking.
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Affiliation(s)
- Hilary Renshaw
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Praveen R Juvvadi
- Department of Pediatrics, Duke University Medical Center, Durham, NC, 27710, USA.
| | - D Christopher Cole
- Department of Pediatrics, Duke University Medical Center, Durham, NC, 27710, USA
| | - William J Steinbach
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, 27710, USA; Department of Pediatrics, Duke University Medical Center, Durham, NC, 27710, USA.
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18
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Marzo MG, Griswold JM, Markus SM. Pac1/LIS1 stabilizes an uninhibited conformation of dynein to coordinate its localization and activity. Nat Cell Biol 2020; 22:559-569. [PMID: 32341548 DOI: 10.1038/s41556-020-0492-1] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 02/23/2020] [Indexed: 12/20/2022]
Abstract
Dynein is a microtubule motor that transports many different cargos in various cell types and contexts. How dynein is regulated to perform these activities with spatial and temporal precision remains unclear. Human dynein is regulated by autoinhibition, whereby intermolecular contacts limit motor activity. Whether this mechanism is conserved throughout evolution, whether it can be affected by extrinsic factors, and its role in regulating dynein function remain unclear. Here, we use a combination of negative stain electron microscopy, single-molecule assays, genetic, and cell biological techniques to show that autoinhibition is conserved in budding yeast, and plays a key role in coordinating in vivo dynein function. Moreover, we find that the Lissencephaly-related protein, LIS1 (Pac1 in yeast), plays an important role in regulating dynein autoinhibition. Our studies demonstrate that, rather than inhibiting dynein motility, Pac1/LIS1 promotes dynein activity by stabilizing the uninhibited conformation, which ensures appropriate dynein localization and activity in cells.
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Affiliation(s)
- Matthew G Marzo
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - Jacqueline M Griswold
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - Steven M Markus
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA.
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19
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Kaur N, Chen W, Fei Z, Wintermantel WM. Differences in gene expression in whitefly associated with CYSDV-infected and virus-free melon, and comparison with expression in whiteflies fed on ToCV- and TYLCV-infected tomato. BMC Genomics 2019; 20:654. [PMID: 31416422 PMCID: PMC6694564 DOI: 10.1186/s12864-019-5999-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 07/26/2019] [Indexed: 01/31/2023] Open
Abstract
Background Cucurbit yellow stunting disorder virus (CYSDV; genus Crinivirus, Closteroviridae) is transmitted in a semipersistent manner by the whitefly, Bemisia tabaci, and is efficiently transmitted by the widely prevalent B. tabaci cryptic species, MEAM1. In this study, we compared transcriptome profiles of B. tabaci MEAM1, after 24 h, 72 h and 7 days of acquisition feeding on melon plants infected with CYSDV (CYSDV-whiteflies) with those fed on virus-free melon, using RNA-Seq technology. We also compared transcriptome profiles with whiteflies fed on tomato plants separately infected with Tomato chlorosis virus (ToCV), a crinivirus closely related to CYSDV, and Tomato yellow leaf curl virus (TYLCV), a member of the genus Begomovirus, which has a distinctly different mode of transmission and their respective virus-free controls, to find common gene expression changes among viruliferous whiteflies feeding on different host plants infected with distinct (TYLCV) and related (CYSDV and ToCV) viruses. Results A total of 275 differentially expressed genes (DEGs) were identified in CYSDV-whiteflies, with 3 DEGs at 24 h, 221 DEGs at 72 h, and 51 DEGs at 7 days of virus acquisition. Changes in genes encoding orphan genes (54 genes), phosphatidylethanolamine-binding proteins (PEBP) (20 genes), and AAA-ATPase domain containing proteins (10 genes) were associated with the 72 h time point. Several more orphan genes (20 genes) were differentially expressed at 7 days. A total of 59 common DEGs were found between CYSDV-whiteflies and ToCV-whiteflies, which included 20 orphan genes and 6 lysosomal genes. A comparison of DEGs across the three different virus-host systems revealed 14 common DEGs, among which, eight showed similar and significant up-regulation in CYSDV-whiteflies at 72 h and TYLCV-whiteflies at 24 h, while down-regulation of the same genes was observed in ToCV-whiteflies at 72 h. Conclusions Dynamic gene expression changes occurred in CYSDV-whiteflies after 72 h feeding, with decreased gene expression changes associated with 7 days of CYSDV acquisition. Similarities in gene expression changes among CYSDV-whiteflies, ToCV-whiteflies and TYLCV-whiteflies suggest the possible involvement of common genes or pathways for virus acquisition and transmission by whiteflies, even for viruses with distinctly different modes of transmission. Electronic supplementary material The online version of this article (10.1186/s12864-019-5999-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Navneet Kaur
- USDA-ARS, Crop Improvement and Protection Research, 1636 East Alisal Street, Salinas, CA, 93905, USA.,Present Address: Driscoll's Inc., 151 Silliman Rd., Watsonville, CA, 95076, USA
| | - Wenbo Chen
- Boyce Thompson Institute, 533 Tower Road, Ithaca, New York, 14853-1801, USA
| | - Zhangjun Fei
- Boyce Thompson Institute, 533 Tower Road, Ithaca, New York, 14853-1801, USA.,USDA-ARS, Robert W. Holley Center for Agriculture and Health, 538 Tower Road, Ithaca, New York, 14853-2901, USA
| | - William M Wintermantel
- USDA-ARS, Crop Improvement and Protection Research, 1636 East Alisal Street, Salinas, CA, 93905, USA.
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20
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Marzo MG, Griswold JM, Ruff KM, Buchmeier RE, Fees CP, Markus SM. Molecular basis for dyneinopathies reveals insight into dynein regulation and dysfunction. eLife 2019; 8:47246. [PMID: 31364990 PMCID: PMC6733598 DOI: 10.7554/elife.47246] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 07/30/2019] [Indexed: 12/22/2022] Open
Abstract
Cytoplasmic dynein plays critical roles within the developing and mature nervous systems, including effecting nuclear migration, and retrograde transport of various cargos. Unsurprisingly, mutations in dynein are causative of various developmental neuropathies and motor neuron diseases. These ‘dyneinopathies’ define a broad spectrum of diseases with no known correlation between mutation identity and disease state. To circumvent complications associated with dynein studies in human cells, we employed budding yeast as a screening platform to characterize the motility properties of seventeen disease-correlated dynein mutants. Using this system, we determined the molecular basis for several classes of etiologically related diseases. Moreover, by engineering compensatory mutations, we alleviated the mutant phenotypes in two of these cases, one of which we confirmed with recombinant human dynein. In addition to revealing molecular insight into dynein regulation, our data provide additional evidence that the type of disease may in fact be dictated by the degree of dynein dysfunction. Motor proteins maintain order by transporting biomolecules and various structures within living cells. Dynein is one such motor that moves many types of cargoes along tracks called microtubules, which are spread across the cell’s interior. This motor is particularly important in nerve cells, which can be very long and thus depend heavily on motor proteins to ensure cargoes end up where they are needed. This becomes especially apparent in human diseases that arise as a consequence of mutations in the genes that produce components of the dynein motor. It is assumed that these genetic changes simply prevent dynein from working properly, which ultimately affects the health and survival of cells. However, it is currently unknown what specific effect these mutations have on dynein’s role within the cell, and how these changes lead to particular diseases. Marzo et al. have now used dynein from a budding yeast to closely examine 17 mutations in the dynein gene that are associated with developmental and/or motor neuron diseases in humans. For each mutation, various aspects of how dynein moves (e.g. average speed, distance travelled) were measured and quantitatively compared. The results show that the severity of the effect of each mutation can be directly correlated with the type of disease caused by the mutation. In particular, mutations that lead to less severe defects are found in patients that suffer from various motor neuron diseases, while more severe dynein mutations are found in patients with developmental brain disorders. Marzo et al. confirmed the likely structural changes that caused the defects in dynein’s activity in two of the 17 cases, by engineering additional, restorative mutations that lessened the effects of the primary mutation. These findings reveal links between the molecular impact of defects in the dynein gene and human health. They also confirm that budding yeast is a powerful tool for investigating newly discovered dynein mutations that correlate with disease. This study provides a potential system that could be used to screen drugs that might lessen the effects of specific dynein mutations. However, further work is needed to determine how effective this system will be for drug discovery.
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Affiliation(s)
- Matthew G Marzo
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
| | - Jacqueline M Griswold
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
| | - Kristina M Ruff
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
| | - Rachel E Buchmeier
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
| | - Colby P Fees
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, United States
| | - Steven M Markus
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
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21
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Estrem C, Moore JK. Astral microtubule forces alter nuclear organization and inhibit DNA repair in budding yeast. Mol Biol Cell 2019; 30:2000-2013. [PMID: 31067146 PMCID: PMC6727761 DOI: 10.1091/mbc.e18-12-0808] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Dividing cells must balance the maintenance of genome integrity with the generation of cytoskeletal forces that control chromosome position. In this study, we investigate how forces on astral microtubules impact the genome during cell division by using live-cell imaging of the cytoskeleton, chromatin, and DNA damage repair in budding yeast. Our results demonstrate that dynein-dependent forces on astral microtubules are propagated through the spindle during nuclear migration and when in excess can increase the frequency of double-stranded breaks (DSBs). Under these conditions, we find that homology-directed repair of DSBs is delayed, indicating antagonism between nuclear migration and the mechanism of homology-directed repair. These effects are partially rescued by mutants that weaken pericentric cohesion or mutants that decrease constriction on the nucleus as it moves through the bud neck. We propose that minimizing nuclear movement aids in finding a donor strand for homologous recombination.
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Affiliation(s)
- Cassi Estrem
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045
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22
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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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23
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Bergman ZJ, Wong J, Drubin DG, Barnes G. Microtubule dynamics regulation reconstituted in budding yeast lysates. J Cell Sci 2018; 132:jcs.219386. [PMID: 30185524 DOI: 10.1242/jcs.219386] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 08/23/2018] [Indexed: 01/14/2023] Open
Abstract
Microtubules (MTs) are important for cellular structure, transport of cargoes and segregation of chromosomes and organelles during mitosis. The stochastic growth and shrinkage of MTs, known as dynamic instability, is necessary for these functions. Previous studies to determine how individual MT-associated proteins (MAPs) affect MT dynamics have been performed either through in vivo studies, which provide limited opportunity for observation of individual MTs or manipulation of conditions, or in vitro studies, which focus either on purified proteins, and therefore lack cellular complexity, or on cell extracts made from genetically intractable organisms. In order to investigate the ensemble activities of all MAPs on MT dynamics using lysates made from a genetically tractable organism, we developed a cell-free assay for budding yeast lysates using total internal reflection fluorescence (TIRF) microscopy. Lysates were prepared from yeast strains expressing GFP-tubulin. MT polymerization from pre-assembled MT seeds adhered to a coverslip was observed in real time. Through use of cell division cycle (cdc) and MT depolymerase mutants, we found that MT polymerization and dynamic instability are dependent on the cell cycle state and the activities of specific MAPs.
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Affiliation(s)
- Zane J Bergman
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Jonathan Wong
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - David G Drubin
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Georjana Barnes
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
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24
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Wu SZ, Bezanilla M. Actin and microtubule cross talk mediates persistent polarized growth. J Cell Biol 2018; 217:3531-3544. [PMID: 30061106 PMCID: PMC6168251 DOI: 10.1083/jcb.201802039] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 05/08/2018] [Accepted: 07/10/2018] [Indexed: 11/25/2022] Open
Abstract
How the actin and microtubule cytoskeletons work together during diverse cellular functions is unclear. Wu et al. describe an apical actin pool in plant cells organized by a microtubule template at the site of polarized growth. Disconnecting the two cytoskeletons by removing class VIII myosins alters both cytoskeletal structures and impairs polarized growth. Coordination between actin and microtubules is important for numerous cellular processes in diverse eukaryotes. In plants, tip-growing cells require actin for cell expansion and microtubules for orientation of cell expansion, but how the two cytoskeletons are linked is an open question. In tip-growing cells of the moss Physcomitrella patens, we show that an actin cluster near the cell apex dictates the direction of rapid cell expansion. Formation of this structure depends on the convergence of microtubules near the cell tip. We discovered that microtubule convergence requires class VIII myosin function, and actin is necessary for myosin VIII–mediated focusing of microtubules. The loss of myosin VIII function affects both networks, indicating functional connections among the three cytoskeletal components. Our data suggest that microtubules direct localization of formins, actin nucleation factors, that generate actin filaments further focusing microtubules, thereby establishing a positive feedback loop ensuring that actin polymerization and cell expansion occur at a defined site resulting in persistent polarized growth.
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Affiliation(s)
- Shu-Zon Wu
- Department of Biological Sciences, Dartmouth College, Hanover, NH
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25
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The actin capping protein in Aspergillus nidulans enhances dynein function without significantly affecting Arp1 filament assembly. Sci Rep 2018; 8:11419. [PMID: 30061726 PMCID: PMC6065395 DOI: 10.1038/s41598-018-29818-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 07/18/2018] [Indexed: 11/08/2022] Open
Abstract
The minus-end-directed microtubule motor cytoplasmic dynein requires the dynactin complex for in vivo functions. The backbone of the vertebrate dynactin complex is the Arp1 (actin-related protein 1) mini-filament whose barbed end binds to the heterodimeric actin capping protein. However, it is unclear whether the capping protein is a dynactin component in lower eukaryotic organisms, especially because it does not appear to be a component of the budding yeast dynactin complex. Here our biochemical data show that the capping protein is a component of the dynactin complex in the filamentous fungus Aspergillus nidulans. Moreover, deletion of the gene encoding capping protein alpha (capA) results in a defect in both nuclear distribution and early-endosome transport, two dynein-mediated processes. However, the defect in either process is less severe than that exhibited by a dynein heavy chain mutant or the ∆p25 mutant of dynactin. In addition, loss of capping protein does not significantly affect the assembly of the dynactin Arp1 filament or the formation of the dynein-dynactin-∆C-HookA (Hook in A. nidulans) complex. These results suggest that fungal capping protein is not important for Arp1 filament assembly but its presence is required for enhancing dynein function in vivo.
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26
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Schmit HL, Kraft LM, Lee-Smith CF, Lackner LL. The role of mitochondria in anchoring dynein to the cell cortex extends beyond clustering the anchor protein. Cell Cycle 2018; 17:1345-1357. [PMID: 29976118 PMCID: PMC6110599 DOI: 10.1080/15384101.2018.1480226] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Organelle distribution is regulated over the course of the cell cycle to ensure that each of the cells produced at the completion of division inherits a full complement of organelles. In yeast, the protein Num1 functions in the positioning and inheritance of two essential organelles, mitochondria and the nucleus. Specifically, Num1 anchors mitochondria as well as dynein to the cell cortex, and this anchoring activity is required for proper mitochondrial distribution and dynein-mediated nuclear inheritance. The assembly of Num1 into clusters at the plasma membrane is critical for both of its anchoring functions. We have previously shown that mitochondria drive the assembly of Num1 clusters and that these mitochondria-assembled Num1 clusters serve as cortical attachment sites for dynein. Here we further examine the role for mitochondria in dynein anchoring. Using a GFP-αGFP nanobody targeting system, we synthetically clustered Num1 on eisosomes to bypass the requirement for mitochondria in Num1 cluster formation. Utilizing this system, we found that mitochondria positively impact the ability of synthetically clustered Num1 to anchor dynein and support dynein function even when mitochondria are no longer required for cluster formation. Thus, the role of mitochondria in regulating dynein function extends beyond simply concentrating Num1; mitochondria likely promote an arrangement of Num1 within a cluster that is competent for dynein anchoring. This functional dependency between mitochondrial and nuclear positioning pathways likely serves as a mechanism to order and integrate major cellular organization systems over the course of the cell cycle.
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Affiliation(s)
- Heidi L Schmit
- a Department of Molecular Biosciences , Northwestern University , Evanston , IL , USA
| | - Lauren M Kraft
- a Department of Molecular Biosciences , Northwestern University , Evanston , IL , USA
| | - Conor F Lee-Smith
- a Department of Molecular Biosciences , Northwestern University , Evanston , IL , USA
| | - Laura L Lackner
- a Department of Molecular Biosciences , Northwestern University , Evanston , IL , USA
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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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28
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Riquelme M, Aguirre J, Bartnicki-García S, Braus GH, Feldbrügge M, Fleig U, Hansberg W, Herrera-Estrella A, Kämper J, Kück U, Mouriño-Pérez RR, Takeshita N, Fischer R. Fungal Morphogenesis, from the Polarized Growth of Hyphae to Complex Reproduction and Infection Structures. Microbiol Mol Biol Rev 2018; 82:e00068-17. [PMID: 29643171 PMCID: PMC5968459 DOI: 10.1128/mmbr.00068-17] [Citation(s) in RCA: 183] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Filamentous fungi constitute a large group of eukaryotic microorganisms that grow by forming simple tube-like hyphae that are capable of differentiating into more-complex morphological structures and distinct cell types. Hyphae form filamentous networks by extending at their tips while branching in subapical regions. Rapid tip elongation requires massive membrane insertion and extension of the rigid chitin-containing cell wall. This process is sustained by a continuous flow of secretory vesicles that depends on the coordinated action of the microtubule and actin cytoskeletons and the corresponding motors and associated proteins. Vesicles transport cell wall-synthesizing enzymes and accumulate in a special structure, the Spitzenkörper, before traveling further and fusing with the tip membrane. The place of vesicle fusion and growth direction are enabled and defined by the position of the Spitzenkörper, the so-called cell end markers, and other proteins involved in the exocytic process. Also important for tip extension is membrane recycling by endocytosis via early endosomes, which function as multipurpose transport vehicles for mRNA, septins, ribosomes, and peroxisomes. Cell integrity, hyphal branching, and morphogenesis are all processes that are largely dependent on vesicle and cytoskeleton dynamics. When hyphae differentiate structures for asexual or sexual reproduction or to mediate interspecies interactions, the hyphal basic cellular machinery may be reprogrammed through the synthesis of new proteins and/or the modification of protein activity. Although some transcriptional networks involved in such reprogramming of hyphae are well studied in several model filamentous fungi, clear connections between these networks and known determinants of hyphal morphogenesis are yet to be established.
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Affiliation(s)
- Meritxell Riquelme
- Department of Microbiology, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California, Mexico
| | - Jesús Aguirre
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
| | - Salomon Bartnicki-García
- Department of Microbiology, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California, Mexico
| | - Gerhard H Braus
- Department of Molecular Microbiology and Genetics and Goettingen Center for Molecular Biosciences (GZMB), University of Goettingen, Goettingen, Germany
| | - Michael Feldbrügge
- Institute for Microbiology, Heinrich Heine University Düsseldorf, Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
| | - Ursula Fleig
- Institute for Functional Genomics of Microorganisms, Heinrich Heine University Düsseldorf, Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
| | - Wilhelm Hansberg
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico
| | - Alfredo Herrera-Estrella
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Irapuato, Mexico
| | - Jörg Kämper
- Karlsruhe Institute of Technology-South Campus, Institute for Applied Biosciences, Karlsruhe, Germany
| | - Ulrich Kück
- Ruhr University Bochum, Lehrstuhl für Allgemeine und Molekulare Botanik, Bochum, Germany
| | - Rosa R Mouriño-Pérez
- Department of Microbiology, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California, Mexico
| | - Norio Takeshita
- University of Tsukuba, Faculty of Life and Environmental Sciences, Tsukuba, Japan
| | - Reinhard Fischer
- Karlsruhe Institute of Technology-South Campus, Institute for Applied Biosciences, Karlsruhe, Germany
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29
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Shin M, van Leeuwen J, Boone C, Bretscher A. Yeast Aim21/Tda2 both regulates free actin by reducing barbed end assembly and forms a complex with Cap1/Cap2 to balance actin assembly between patches and cables. Mol Biol Cell 2018; 29:923-936. [PMID: 29467252 PMCID: PMC5896931 DOI: 10.1091/mbc.e17-10-0592] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Yeast Aim21 is recruited by the SH3-containing proteins Bbc1 and Abp1 to patches and, with Tda2, reduces barbed end assembly to balance the distribution of actin between patches and cables. Aim21/Tda2 also interacts with Cap1/Cap2, revealing a complex interplay between actin assembly regulators. How cells balance the incorporation of actin into diverse structures is poorly understood. In budding yeast, a single actin monomer pool is used to build both actin cables involved in polarized growth and actin cortical patches involved in endocytosis. Here we report how Aim21/Tda2 is recruited to the cortical region of actin patches, where it negatively regulates actin assembly to elevate the available actin monomer pool. Aim21 has four polyproline regions and is recruited by two SH3-containing patch proteins, Bbc1 and Abp1. The C-terminal region, which is required for its function, binds Tda2. Cell biological and biochemical data reveal that Aim21/Tda2 is a negative regulator of barbed end filamentous actin (F-actin) assembly, and this activity is necessary for efficient endocytosis and plays a pivotal role in balancing the distribution of actin between cables and patches. Aim21/Tda2 also forms a complex with the F-actin barbed end capping protein Cap1/Cap2, revealing an interplay between regulators and showing the complexity of regulation of barbed end assembly.
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Affiliation(s)
- Myungjoo Shin
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
| | | | - Charles Boone
- Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Anthony Bretscher
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
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30
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Zhang N, Yao LL, Li XD. Regulation of class V myosin. Cell Mol Life Sci 2018; 75:261-273. [PMID: 28730277 PMCID: PMC11105390 DOI: 10.1007/s00018-017-2599-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 06/27/2017] [Accepted: 07/17/2017] [Indexed: 01/26/2023]
Abstract
Class V myosin (myosin-5) is a molecular motor that functions as an organelle transporter. The activation of myosin-5's motor function has long been known to be associated with a transition from the folded conformation in the off-state to the extended conformation in the on-state, but only recently have we begun to understand the underlying mechanism. The globular tail domain (GTD) of myosin-5 has been identified as the inhibitory domain and has recently been shown to function as a dimer in regulating the motor function. The folded off-state of myosin-5 is stabilized by multiple intramolecular interactions, including head-GTD interactions, GTD-GTD interactions, and interactions between the GTD and the C-terminus of the first coiled-coil segment. Any cellular factor that affects these intramolecular interactions and thus the stability of the folded conformation of myosin-5 would be expected to regulate myosin-5 motor function. Both the adaptor proteins of myosin-5 and Ca2+ are potential regulators of myosin-5 motor function, because they can destabilize its folded conformation. A combination of these regulators provides a versatile scheme in regulating myosin-5 motor function in the cell.
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Affiliation(s)
- Ning Zhang
- Group of Cell Motility and Muscle Contraction, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Lin-Lin Yao
- Group of Cell Motility and Muscle Contraction, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Xiang-Dong Li
- Group of Cell Motility and Muscle Contraction, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
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31
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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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32
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Lengefeld J, Yen E, Chen X, Leary A, Vogel J, Barral Y. Spatial cues and not spindle pole maturation drive the asymmetry of astral microtubules between new and preexisting spindle poles. Mol Biol Cell 2017; 29:10-28. [PMID: 29142076 PMCID: PMC5746063 DOI: 10.1091/mbc.e16-10-0725] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 10/31/2017] [Accepted: 11/07/2017] [Indexed: 11/17/2022] Open
Abstract
The distinct behavior of the spindle pole bodies (SPBs) during spindle orientation in yeast metaphase does not result from them being differently mature, but astral microtubule organization correlates with the subcellular position rather than the age of the SPBs. In many asymmetrically dividing cells, the microtubule-organizing centers (MTOCs; mammalian centrosome and yeast spindle pole body [SPB]) nucleate more astral microtubules on one of the two spindle poles than the other. This differential activity generally correlates with the age of MTOCs and contributes to orienting the mitotic spindle within the cell. The asymmetry might result from the two MTOCs being in distinctive maturation states. We investigated this model in budding yeast. Using fluorophores with different maturation kinetics to label the outer plaque components of the SPB, we found that the Cnm67 protein is mobile, whereas Spc72 is not. However, these two proteins were rapidly as abundant on both SPBs, indicating that SPBs mature more rapidly than anticipated. Superresolution microscopy confirmed this finding for Spc72 and for the γ-tubulin complex. Moreover, astral microtubule number and length correlated with the subcellular localization of SPBs rather than their age. Kar9-dependent orientation of the spindle drove the differential activity of the SPBs in astral microtubule organization rather than intrinsic differences between the spindle poles. Together, our data establish that Kar9 and spatial cues, rather than the kinetics of SPB maturation, control the asymmetry of astral microtubule organization between the preexisting and new SPBs.
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Affiliation(s)
- Jette Lengefeld
- Department of Biology, Institute of Biochemistry, ETH Zurich, 8093 Zurich, Switzerland
| | - Eric Yen
- Department of Biology, McGill University, Montreal, QC H3G 0B1, Canada
| | - Xiuzhen Chen
- Department of Biology, Institute of Biochemistry, ETH Zurich, 8093 Zurich, Switzerland
| | - Allen Leary
- Department of Biology, McGill University, Montreal, QC H3G 0B1, Canada
| | - Jackie Vogel
- Department of Biology, McGill University, Montreal, QC H3G 0B1, Canada
| | - Yves Barral
- Department of Biology, Institute of Biochemistry, ETH Zurich, 8093 Zurich, Switzerland
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33
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Stoddard PR, Williams TA, Garner E, Baum B. Evolution of polymer formation within the actin superfamily. Mol Biol Cell 2017; 28:2461-2469. [PMID: 28904122 PMCID: PMC5597319 DOI: 10.1091/mbc.e15-11-0778] [Citation(s) in RCA: 18] [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: 05/22/2017] [Revised: 07/13/2017] [Accepted: 07/18/2017] [Indexed: 01/02/2023] Open
Abstract
While many are familiar with actin as a well-conserved component of the eukaryotic cytoskeleton, it is less often appreciated that actin is a member of a large superfamily of structurally related protein families found throughout the tree of life. Actin-related proteins include chaperones, carbohydrate kinases, and other enzymes, as well as a staggeringly diverse set of proteins that use the energy from ATP hydrolysis to form dynamic, linear polymers. Despite differing widely from one another in filament structure and dynamics, these polymers play important roles in ordering cell space in bacteria, archaea, and eukaryotes. It is not known whether these polymers descended from a single ancestral polymer or arose multiple times by convergent evolution from monomeric actin-like proteins. In this work, we provide an overview of the structures, dynamics, and functions of this diverse set. Then, using a phylogenetic analysis to examine actin evolution, we show that the actin-related protein families that form polymers are more closely related to one another than they are to other nonpolymerizing members of the actin superfamily. Thus all the known actin-like polymers are likely to be the descendants of a single, ancestral, polymer-forming actin-like protein.
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Affiliation(s)
- Patrick R Stoddard
- Molecular and Cellular Biology, Faculty of Arts and Sciences Center for Systems Biology, Harvard University, Cambridge, MA 02138
| | - Tom A Williams
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
| | - Ethan Garner
- Molecular and Cellular Biology, Faculty of Arts and Sciences Center for Systems Biology, Harvard University, Cambridge, MA 02138
| | - Buzz Baum
- MRC-Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK
- Institute of Physics of Living Systems, University College London, London WC1E 6BT, UK
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34
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Shulist K, Yen E, Kaitna S, Leary A, Decterov A, Gupta D, Vogel J. Interrogation of γ-tubulin alleles using high-resolution fitness measurements reveals a distinct cytoplasmic function in spindle alignment. Sci Rep 2017; 7:11398. [PMID: 28900268 PMCID: PMC5595808 DOI: 10.1038/s41598-017-11789-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 08/30/2017] [Indexed: 01/08/2023] Open
Abstract
γ-Tubulin has a well-established role in nucleating the assembly of microtubules, yet how phosphorylation regulates its activity remains unclear. Here, we use a time-resolved, fitness-based SGA approach to compare two γ-tubulin alleles, and find that the genetic interaction profile of γtub-Y362E is enriched in spindle positioning and cell polarity genes relative to that of γtub-Y445D, which is enriched in genes involved in spindle assembly and stability. In γtub-Y362E cells, we find a defect in spindle alignment and an increase in the number of astral microtubules at both spindle poles. Our results suggest that the γtub-Y362E allele is a separation-of-function mutation that reveals a role for γ-tubulin phospho-regulation in spindle alignment. We propose that phosphorylation of the evolutionarily conserved Y362 residue of budding yeast γ-tubulin contributes to regulating the number of astral microtubules associated with spindle poles, and promoting efficient pre-anaphase spindle alignment.
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Affiliation(s)
- Kristian Shulist
- Department of Biology, McGill University, 3649 Promenade Sir William Osler, Montreal, Quebec, H3G 0B1, Canada
| | - Eric Yen
- Department of Biology, McGill University, 3649 Promenade Sir William Osler, Montreal, Quebec, H3G 0B1, Canada
| | - Susanne Kaitna
- Department of Biology, McGill University, 3649 Promenade Sir William Osler, Montreal, Quebec, H3G 0B1, Canada
| | - Allen Leary
- Department of Biology, McGill University, 3649 Promenade Sir William Osler, Montreal, Quebec, H3G 0B1, Canada
| | - Alexandra Decterov
- Department of Biology, McGill University, 3649 Promenade Sir William Osler, Montreal, Quebec, H3G 0B1, Canada
| | - Debarun Gupta
- Department of Biology, McGill University, 3649 Promenade Sir William Osler, Montreal, Quebec, H3G 0B1, Canada
| | - Jackie Vogel
- Department of Biology, McGill University, 3649 Promenade Sir William Osler, Montreal, Quebec, H3G 0B1, Canada.
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35
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Kraft LM, Lackner LL. Mitochondria-driven assembly of a cortical anchor for mitochondria and dynein. J Cell Biol 2017; 216:3061-3071. [PMID: 28835466 PMCID: PMC5626545 DOI: 10.1083/jcb.201702022] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 06/01/2017] [Accepted: 07/17/2017] [Indexed: 12/21/2022] Open
Abstract
Kraft and Lackner demonstrate that mitochondria drive the assembly of a tether, which serves to stably anchor the organelle itself as well as dynein to the plasma membrane. Thus, mitochondria–plasma membrane tethering influences when and where dynein is anchored, adding to the growing list of interorganelle contact site functions. Interorganelle contacts facilitate communication between organelles and impact fundamental cellular functions. In this study, we examine the assembly of the MECA (mitochondria–endoplasmic reticulum [ER]–cortex anchor), which tethers mitochondria to the ER and plasma membrane. We find that the assembly of Num1, the core component of MECA, requires mitochondria. Once assembled, Num1 clusters persistently anchor mitochondria to the cell cortex. Num1 clusters also function to anchor dynein to the plasma membrane, where dynein captures and walks along astral microtubules to help orient the mitotic spindle. We find that dynein is anchored by Num1 clusters that have been assembled by mitochondria. When mitochondrial inheritance is inhibited, Num1 clusters are not assembled in the bud, and defects in dynein-mediated spindle positioning are observed. The mitochondria-dependent assembly of a dual-function cortical anchor provides a mechanism to integrate the positioning and inheritance of the two essential organelles and expands the function of organelle contact sites.
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Affiliation(s)
- Lauren M Kraft
- Department of Molecular Biosciences, Northwestern University, Evanston, IL
| | - Laura L Lackner
- Department of Molecular Biosciences, Northwestern University, Evanston, IL
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36
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Geymonat M, Segal M. Intrinsic and Extrinsic Determinants Linking Spindle Pole Fate, Spindle Polarity, and Asymmetric Cell Division in the Budding Yeast S. cerevisiae. Results Probl Cell Differ 2017; 61:49-82. [PMID: 28409300 DOI: 10.1007/978-3-319-53150-2_3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The budding yeast S. cerevisiae is a powerful model to understand the multiple layers of control driving an asymmetric cell division. In budding yeast, asymmetric targeting of the spindle poles to the mother and bud cell compartments respectively orients the mitotic spindle along the mother-bud axis. This program exploits an intrinsic functional asymmetry arising from the age distinction between the spindle poles-one inherited from the preceding division and the other newly assembled. Extrinsic mechanisms convert this age distinction into differential fate. Execution of this program couples spindle orientation with the segregation of the older spindle pole to the bud. Remarkably, similar stereotyped patterns of inheritance occur in self-renewing stem cell divisions underscoring the general importance of studying spindle polarity and differential fate in yeast. Here, we review the mechanisms accounting for this pivotal interplay between intrinsic and extrinsic asymmetries that translate spindle pole age into differential fate.
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Affiliation(s)
- Marco Geymonat
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
| | - Marisa Segal
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK.
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37
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Dewey EB, Johnston CA. Diverse mitotic functions of the cytoskeletal cross-linking protein Shortstop suggest a role in Dynein/Dynactin activity. Mol Biol Cell 2017; 28:2555-2568. [PMID: 28747439 PMCID: PMC5597327 DOI: 10.1091/mbc.e17-04-0219] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 06/19/2017] [Accepted: 07/19/2017] [Indexed: 12/20/2022] Open
Abstract
Shortstop (Shot), an actin–microtubule cross-linking protein, interacts with the Dynactin component Arp-1 to control mitotic spindle assembly and positioning in Drosophila. Shot is important for proper chromosome congression and segregation. Loss of Shot in epithelial tissue leads to significant apoptosis, which when blocked leads to epithelial–mesenchymal transition-like changes. Proper assembly and orientation of the bipolar mitotic spindle is critical to the fidelity of cell division. Mitotic precision fundamentally contributes to cell fate specification, tissue development and homeostasis, and chromosome distribution within daughter cells. Defects in these events are thought to contribute to several human diseases. The underlying mechanisms that function in spindle morphogenesis and positioning remain incompletely defined, however. Here we describe diverse roles for the actin-microtubule cross-linker Shortstop (Shot) in mitotic spindle function in Drosophila. Shot localizes to mitotic spindle poles, and its knockdown results in an unfocused spindle pole morphology and a disruption of proper spindle orientation. Loss of Shot also leads to chromosome congression defects, cell cycle progression delay, and defective chromosome segregation during anaphase. These mitotic errors trigger apoptosis in Drosophila epithelial tissue, and blocking this apoptotic response results in a marked induction of the epithelial–mesenchymal transition marker MMP-1. The actin-binding domain of Shot directly interacts with Actin-related protein-1 (Arp-1), a key component of the Dynein/Dynactin complex. Knockdown of Arp-1 phenocopies Shot loss universally, whereas chemical disruption of F-actin does so selectively. Our work highlights novel roles for Shot in mitosis and suggests a mechanism involving Dynein/Dynactin activation.
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Affiliation(s)
- Evan B Dewey
- Department of Biology, University of New Mexico, Albuquerque, NM 87131
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38
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Lawrimore J, Barry TM, Barry RM, York AC, Friedman B, Cook DM, Akialis K, Tyler J, Vasquez P, Yeh E, Bloom K. Microtubule dynamics drive enhanced chromatin motion and mobilize telomeres in response to DNA damage. Mol Biol Cell 2017; 28:1701-1711. [PMID: 28450453 PMCID: PMC5469612 DOI: 10.1091/mbc.e16-12-0846] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 03/28/2017] [Accepted: 04/18/2017] [Indexed: 12/13/2022] Open
Abstract
Mechanisms that drive DNA damage-induced chromosome mobility include relaxation of external tethers to the nuclear envelope and internal chromatin–chromatin tethers. Together with microtubule dynamics, these can mobilize the genome in response to DNA damage. Chromatin exhibits increased mobility on DNA damage, but the biophysical basis for this behavior remains unknown. To explore the mechanisms that drive DNA damage–induced chromosome mobility, we use single-particle tracking of tagged chromosomal loci during interphase in live yeast cells together with polymer models of chromatin chains. Telomeres become mobilized from sites on the nuclear envelope and the pericentromere expands after exposure to DNA-damaging agents. The magnitude of chromatin mobility induced by a single double-strand break requires active microtubule function. These findings reveal how relaxation of external tethers to the nuclear envelope and internal chromatin–chromatin tethers, together with microtubule dynamics, can mobilize the genome in response to DNA damage.
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Affiliation(s)
- Josh Lawrimore
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Timothy M Barry
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Raymond M Barry
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Alyssa C York
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Brandon Friedman
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Diana M Cook
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Kristen Akialis
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Jolien Tyler
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Paula Vasquez
- Department of Mathematics, University of South Carolina, Columbia, SC 29208
| | - Elaine Yeh
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Kerry Bloom
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
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Gibeaux R, Politi AZ, Philippsen P, Nédélec F. Mechanism of nuclear movements in a multinucleated cell. Mol Biol Cell 2017; 28:645-660. [PMID: 28077618 PMCID: PMC5328623 DOI: 10.1091/mbc.e16-11-0806] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 01/04/2017] [Accepted: 01/04/2017] [Indexed: 02/06/2023] Open
Abstract
Multinucleated cells are important in many organisms, but the mechanisms governing the movements of nuclei sharing a common cytoplasm are not understood. In the hyphae of the plant pathogenic fungus Ashbya gossypii, nuclei move back and forth, occasionally bypassing each other, preventing the formation of nuclear clusters. This is essential for genetic stability. These movements depend on cytoplasmic microtubules emanating from the nuclei that are pulled by dynein motors anchored at the cortex. Using three-dimensional stochastic simulations with parameters constrained by the literature, we predict the cortical anchor density from the characteristics of nuclear movements. The model accounts for the complex nuclear movements seen in vivo, using a minimal set of experimentally determined ingredients. Of interest, these ingredients power the oscillations of the anaphase spindle in budding yeast, but in A. gossypii, this system is not restricted to a specific nuclear cycle stage, possibly as a result of adaptation to hyphal growth and multinuclearity.
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Affiliation(s)
- Romain Gibeaux
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Antonio Z Politi
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Peter Philippsen
- Molecular Microbiology, Biozentrum, University of Basel, CH-4056 Basel, Switzerland
| | - François Nédélec
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
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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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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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42
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Kim SJ, Lee S, Park HJ, Kang TH, Sagong B, Baek JI, Oh SK, Choi JY, Lee KY, Kim UK. Genetic association of MYH genes with hereditary hearing loss in Korea. Gene 2016; 591:177-182. [DOI: 10.1016/j.gene.2016.07.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 06/15/2016] [Accepted: 07/04/2016] [Indexed: 01/12/2023]
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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: 12] [Impact Index Per Article: 1.5] [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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Lwin KM, Li D, Bretscher A. Kinesin-related Smy1 enhances the Rab-dependent association of myosin-V with secretory cargo. Mol Biol Cell 2016; 27:2450-62. [PMID: 27307583 PMCID: PMC4966985 DOI: 10.1091/mbc.e16-03-0185] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 06/08/2016] [Indexed: 01/21/2023] Open
Abstract
Smy1 is a kinesin-related protein that enhances the association of the Myo2 myosin-V motor with its receptor, the Rab Sec4, on secretory vesicles. This function requires Smy1’s head, coiled-coil, and tail domains and is specific for secretory vesicle transport but not for mitochondrial segregation by Myo2, which also uses a Rab protein, Ypt11. The mechanisms by which molecular motors associate with specific cargo is a central problem in cell organization. The kinesin-like protein Smy1 of budding yeast was originally identified by the ability of elevated levels to suppress a conditional myosin-V mutation (myo2-66), but its function with Myo2 remained mysterious. Subsequently, Myo2 was found to provide an essential role in delivery of secretory vesicles for polarized growth and in the transport of mitochondria for segregation. By isolating and characterizing myo2 smy1 conditional mutants, we uncover the molecular function of Smy1 as a factor that enhances the association of Myo2 with its receptor, the Rab Sec4, on secretory vesicles. The tail of Smy1—which binds Myo2—its central dimerization domain, and its kinesin-like head domain are all necessary for this function. Consistent with this model, overexpression of full-length Smy1 enhances the number of Sec4 receptors and Myo2 motors per transporting secretory vesicle. Rab proteins Sec4 and Ypt11, receptors for essential transport of secretory vesicles and mitochondria, respectively, bind the same region on Myo2, yet Smy1 functions selectively in the transport of secretory vesicles. Thus a kinesin-related protein can function intimately with a myosin-V and its receptor in the transport of a specific cargo.
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Affiliation(s)
- Kyaw Myo Lwin
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
| | - Donghao Li
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
| | - Anthony Bretscher
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
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Bergs A, Ishitsuka Y, Evangelinos M, Nienhaus GU, Takeshita N. Dynamics of Actin Cables in Polarized Growth of the Filamentous Fungus Aspergillus nidulans. Front Microbiol 2016; 7:682. [PMID: 27242709 PMCID: PMC4860496 DOI: 10.3389/fmicb.2016.00682] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 04/26/2016] [Indexed: 12/20/2022] Open
Abstract
Highly polarized growth of filamentous fungi requires a continuous supply of proteins and lipids to the hyphal tip. This transport is managed by vesicle trafficking via the actin and microtubule cytoskeletons and their associated motor proteins. Particularly, actin cables originating from the hyphal tip are essential for hyphal growth. Although, specific marker proteins have been developed to visualize actin cables in filamentous fungi, the exact organization and dynamics of actin cables has remained elusive. Here, we observed actin cables using tropomyosin (TpmA) and Lifeact fused to fluorescent proteins in living Aspergillus nidulans hyphae and studied the dynamics and regulation. GFP tagged TpmA visualized dynamic actin cables formed from the hyphal tip with cycles of elongation and shrinkage. The elongation and shrinkage rates of actin cables were similar and approximately 0.6 μm/s. Comparison of actin markers revealed that high concentrations of Lifeact reduced actin dynamics. Simultaneous visualization of actin cables and microtubules suggests temporally and spatially coordinated polymerization and depolymerization between the two cytoskeletons. Our results provide new insights into the molecular mechanism of ordered polarized growth regulated by actin cables and microtubules.
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Affiliation(s)
- Anna Bergs
- Department of Microbiology, Institute for Applied Bioscience, Karlsruhe Institute of Technology Karlsruhe, Germany
| | - Yuji Ishitsuka
- Institute of Applied Physics, Karlsruhe Institute of Technology Karlsruhe, Germany
| | - Minoas Evangelinos
- Department of Microbiology, Institute for Applied Bioscience, Karlsruhe Institute of TechnologyKarlsruhe, Germany; Faculty of Biology, University of AthensAthens, Greece
| | - G U Nienhaus
- Institute of Applied Physics, Karlsruhe Institute of TechnologyKarlsruhe, Germany; Institute of Toxicology and Genetics, Karlsruhe Institute of TechnologyEggenstein-Leopoldshafen, Germany; Institute of Nanotechnology, Karlsruhe Institute of TechnologyEggenstein-Leopoldshafen, Germany; Department of Physics, University of Illinois at Urbana-ChampaignUrbana-Champaign, IL, USA
| | - Norio Takeshita
- Department of Microbiology, Institute for Applied Bioscience, Karlsruhe Institute of TechnologyKarlsruhe, Germany; Faculty of Life and Environmental Sciences, University of TsukubaTsukuba, Japan
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Knoblach B, Rachubinski RA. Motors, anchors, and connectors: orchestrators of organelle inheritance. Annu Rev Cell Dev Biol 2015; 31:55-81. [PMID: 26443192 DOI: 10.1146/annurev-cellbio-100814-125553] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Organelle inheritance is a process whereby organelles are actively distributed between dividing cells at cytokinesis. Much valuable insight into the molecular mechanisms of organelle inheritance has come from the analysis of asymmetrically dividing cells, which transport a portion of their organelles to the bud while retaining another portion in the mother cell. Common principles apply to the inheritance of all organelles, although individual organelles use specific factors for their partitioning. Inheritance factors can be classified as motors, which are required for organelle transport; anchors, which immobilize organelles at distinct cell structures; or connectors, which mediate the attachment of organelles to motors and anchors. Here, we provide an overview of recent advances in the field of organelle inheritance and highlight how motor, anchor, and connector molecules choreograph the segregation of a multicopy organelle, the peroxisome. We also discuss the role of organelle population control in the generation of cellular diversity.
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Affiliation(s)
- Barbara Knoblach
- Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada;
| | - Richard A Rachubinski
- Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada;
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48
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Jin Y, Weisman LS. The vacuole/lysosome is required for cell-cycle progression. eLife 2015; 4. [PMID: 26322385 PMCID: PMC4586482 DOI: 10.7554/elife.08160] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 08/29/2015] [Indexed: 01/14/2023] Open
Abstract
Organelles are distributed to daughter cells, via inheritance pathways. However, it is unclear whether there are mechanisms beyond inheritance, which ensure that organelles are present in all cells. Here we present the unexpected finding that the yeast vacuole plays a positive essential role in initiation of the cell-cycle. When inheritance fails, a new vacuole is generated. We show that this occurs prior to the next cell-cycle, and gain insight into this alternative pathway. Moreover, we find that a combination of a defect in inheritance with an acute block in the vacuole biogenesis results in the loss of a functional vacuole and a specific arrest of cells in early G1 phase. Furthermore, this role for the vacuole in cell-cycle progression requires an intact TORC1-SCH9 pathway that can only signal from a mature vacuole. These mechanisms may serve as a checkpoint for the presence of the vacuole/lysosome. DOI:http://dx.doi.org/10.7554/eLife.08160.001 Animals, fungi and other eukaryotes have cells that are divided into sub-compartments that are called organelles. Each type of organelle serves a specific purpose that is essential for the life of the cell. Yeast cells have a large organelle called a vacuole; the inside of the vacuole is acidic and contains enzymes that can break down other molecules. Previous studies have shown that when a budding yeast cell buds to produce a new daughter cell, a process ensures that some of the mother's vacuole is transferred to its daughter. However, yeast mutants that fail to inherit some of their mother's vacuole can still survive. This is because an ‘alternative’ mechanism allows the newly forming daughter to generate its own vacuole from scratch. Jin and Weisman now unexpectedly show that a new daughter cell cannot become a mother cell until its new vacuole is formed. The experiments made use of yeast mutants that were defective in the ‘inheritance’ mechanism, and double mutants that were defective in both the inheritance and alternative mechanisms. The experiments also revealed that a signal from the vacuole is required before the yeast cell's nucleus can start the cycle of events that lead to the cell dividing. Jin and Weisman suggest that this newly identified communication between the vacuole and the nucleus may help to ensure that critical organelles are present in all cells. Though it remains unclear why the yeast vacuole is critical for a cell to divide, these findings suggest that the mammalian lysosome (which is similar to the yeast vacuole) may perform a similar critical role in mammals. If this is the case, then understanding how these organelles communicate with the nucleus may provide new insights into how to prevent the uncontrolled growth of tumors and cancer. DOI:http://dx.doi.org/10.7554/eLife.08160.002
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Affiliation(s)
- Yui Jin
- Life Sciences Institute, Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, United States
| | - Lois S Weisman
- Life Sciences Institute, Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, United States
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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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50
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Wang CL, Shaw BD. F-actin localization dynamics during appressorium formation in Colletotrichum graminicola. Mycologia 2015; 108:506-14. [PMID: 26297784 DOI: 10.3852/15-068] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 07/17/2015] [Indexed: 11/10/2022]
Abstract
Appressoria are essential penetration structures for many phytopathogenic fungi. Here F-actin localization dynamics were documented during appressorium formation in vitro and in planta in Colletotrichum graminicola Four discernible stages of dynamic F-actin distribution occurring in a programmed order were documented from differentiation of appressoria to formation of penetration pores: (stage A) from germ tube enlargement to complete expansion of the appressorium; (stage S) septation occurs; (stage L) a long period of low F-actin activity; (stage P) the penetration pore forms. The F-actin subcellular localization corresponded to each stage. A distinct redistribution of actin cables occurred at the transition from stage A to stage S. The in planta assays revealed that F-actin also assembled in invasive hyphae and that actin cables might play an essential role for penetration-peg development. The F-actin localization distribution may be used as a subcellular marker to define the developmental stages during appressorium formation.
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Affiliation(s)
- Chih-Li Wang
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, and Department of Plant Pathology, National Chung Hsing University, Taichung, Taiwan
| | - Brian D Shaw
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas
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