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Fong KK, Davis TN, Asbury CL. Microtubule pivoting enables mitotic spindle assembly in S. cerevisiae. J Cell Biol 2021; 220:211686. [PMID: 33464308 PMCID: PMC7814349 DOI: 10.1083/jcb.202007193] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 12/07/2020] [Accepted: 12/16/2020] [Indexed: 12/17/2022] Open
Abstract
To assemble a bipolar spindle, microtubules emanating from two poles must bundle into an antiparallel midzone, where plus end–directed motors generate outward pushing forces to drive pole separation. Midzone cross-linkers and motors display only modest preferences for antiparallel filaments, and duplicated poles are initially tethered together, an arrangement that instead favors parallel interactions. Pivoting of microtubules around spindle poles might help overcome this geometric bias, but the intrinsic pivoting flexibility of the microtubule–pole interface has not been directly measured, nor has its importance during early spindle assembly been tested. By measuring the pivoting of microtubules around isolated yeast spindle poles, we show that pivoting flexibility can be modified by mutating a microtubule-anchoring pole component, Spc110. By engineering mutants with different flexibilities, we establish the importance of pivoting in vivo for timely pole separation. Our results suggest that passive thermal pivoting can bring microtubules from side-by-side poles into initial contact, but active minus end–directed force generation will be needed to achieve antiparallel alignment.
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Affiliation(s)
- Kimberly K Fong
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | - Trisha N Davis
- Department of Biochemistry, University of Washington, Seattle, WA
| | - Charles L Asbury
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
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2
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Sato M, Kakui Y, Toya M. Tell the Difference Between Mitosis and Meiosis: Interplay Between Chromosomes, Cytoskeleton, and Cell Cycle Regulation. Front Cell Dev Biol 2021; 9:660322. [PMID: 33898463 PMCID: PMC8060462 DOI: 10.3389/fcell.2021.660322] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 03/02/2021] [Indexed: 12/04/2022] Open
Abstract
Meiosis is a specialized style of cell division conserved in eukaryotes, particularly designed for the production of gametes. A huge number of studies to date have demonstrated how chromosomes behave and how meiotic events are controlled. Yeast substantially contributed to the understanding of the molecular mechanisms of meiosis in the past decades. Recently, evidence began to accumulate to draw a perspective landscape showing that chromosomes and microtubules are mutually influenced: microtubules regulate chromosomes, whereas chromosomes also regulate microtubule behaviors. Here we focus on lessons from recent advancement in genetical and cytological studies of the fission yeast Schizosaccharomyces pombe, revealing how chromosomes, cytoskeleton, and cell cycle progression are organized and particularly how these are differentiated in mitosis and meiosis. These studies illuminate that meiosis is strategically designed to fulfill two missions: faithful segregation of genetic materials and production of genetic diversity in descendants through elaboration by meiosis-specific factors in collaboration with general factors.
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Affiliation(s)
- Masamitsu Sato
- Laboratory of Cytoskeletal Logistics, Center for Advanced Biomedical Sciences (TWIns), Waseda University, Tokyo, Japan.,Institute for Advanced Research of Biosystem Dynamics, Waseda Research Institute for Science and Engineering, Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan.,Institute for Medical-Oriented Structural Biology, Waseda University, Tokyo, Japan
| | - Yasutaka Kakui
- Laboratory of Cytoskeletal Logistics, Center for Advanced Biomedical Sciences (TWIns), Waseda University, Tokyo, Japan.,Waseda Institute for Advanced Study, Waseda University, Tokyo, Japan
| | - Mika Toya
- Laboratory of Cytoskeletal Logistics, Center for Advanced Biomedical Sciences (TWIns), Waseda University, Tokyo, Japan.,Institute for Advanced Research of Biosystem Dynamics, Waseda Research Institute for Science and Engineering, Graduate School of Advanced Science and Engineering, Waseda University, Tokyo, Japan.,Major in Bioscience, Global Center for Science and Engineering, Faculty of Science and Engineering, Waseda University, Tokyo, Japan
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3
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Meyer RE, Tipton AR, LaVictoire R, Gorbsky GJ, Dawson DS. Mps1 promotes poleward chromosome movements in meiotic prometaphase. Mol Biol Cell 2021; 32:1020-1032. [PMID: 33788584 PMCID: PMC8101486 DOI: 10.1091/mbc.e20-08-0525-t] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
In prophase of meiosis I, homologous chromosomes pair and become connected by cross-overs. Chiasmata, the connections formed by cross-overs, enable the chromosome pair, called a bivalent, to attach as a single unit to the spindle. When the meiotic spindle forms in prometaphase, most bivalents are associated with one spindle pole and then go through a series of oscillations on the spindle, attaching to and detaching from microtubules until the partners of the bivalent become bioriented—attached to microtubules from opposite sides of the spindle. The conserved kinase, Mps1, is essential for the bivalents to be pulled by microtubules across the spindle in prometaphase. Here we show that MPS1 is needed for efficient triggering of the migration of microtubule-attached kinetochores toward the poles and promotes microtubule depolymerization. Our data support the model Mps1 acts at the kinetochore to coordinate the successful attachment of a microtubule and the triggering of microtubule depolymerization to then move the chromosome.
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Affiliation(s)
- Régis E Meyer
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Aaron R Tipton
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Rebecca LaVictoire
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104
| | - Gary J Gorbsky
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104.,Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104
| | - Dean S Dawson
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104.,Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104
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Prelogović M, Winters L, Milas A, Tolić IM, Pavin N. Pivot-and-bond model explains microtubule bundle formation. Phys Rev E 2019; 100:012403. [PMID: 31499770 DOI: 10.1103/physreve.100.012403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Indexed: 06/10/2023]
Abstract
During mitosis, microtubules form a spindle, which is responsible for proper segregation of the genetic material. A common structural element in a mitotic spindle is a parallel bundle, consisting of two or more microtubules growing from the same origin and held together by cross-linking proteins. An interesting question is what are the physical principles underlying the formation and stability of such microtubule bundles. Here we show, by introducing the pivot-and-bond model, that random angular movement of microtubules around the spindle pole and forces exerted by cross-linking proteins can explain the formation of microtubule bundles as observed in our experiments. The model predicts that stable parallel bundles can form in the presence of either passive crosslinkers or plus-end directed motors, but not minus-end directed motors. In the cases where bundles form, the time needed for their formation depends mainly on the concentration of cross-linking proteins and the angular diffusion of the microtubule. In conclusion, the angular motion drives the alignment of microtubules, which in turn allows the cross-linking proteins to connect the microtubules into a stable bundle.
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Affiliation(s)
- Marcel Prelogović
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb, Croatia
| | - Lora Winters
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany
| | - Ana Milas
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Iva M Tolić
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, 01307 Dresden, Germany
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia
| | - Nenad Pavin
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000 Zagreb, Croatia
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Winters L, Ban I, Prelogović M, Kalinina I, Pavin N, Tolić IM. Pivoting of microtubules driven by minus-end-directed motors leads to spindle assembly. BMC Biol 2019; 17:42. [PMID: 31122217 PMCID: PMC6533735 DOI: 10.1186/s12915-019-0656-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 04/16/2019] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND At the beginning of mitosis, the cell forms a spindle made of microtubules and associated proteins to segregate chromosomes. An important part of spindle architecture is a set of antiparallel microtubule bundles connecting the spindle poles. A key question is how microtubules extending at arbitrary angles form an antiparallel interpolar bundle. RESULTS Here, we show in fission yeast that microtubules meet at an oblique angle and subsequently rotate into antiparallel alignment. Our live-cell imaging approach provides a direct observation of interpolar bundle formation. By combining experiments with theory, we show that microtubules from each pole search for those from the opposite pole by performing random angular movement. Upon contact, two microtubules slide sideways along each other in a directed manner towards the antiparallel configuration. We introduce the contour length of microtubules as a measure of activity of motors that drive microtubule sliding, which we used together with observation of Cut7/kinesin-5 motors and our theory to reveal the minus-end-directed motility of this motor in vivo. CONCLUSION Random rotational motion helps microtubules from the opposite poles to find each other and subsequent accumulation of motors allows them to generate forces that drive interpolar bundle formation.
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Affiliation(s)
- Lora Winters
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, 01307, Dresden, Germany
| | - Ivana Ban
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000, Zagreb, Croatia
| | - Marcel Prelogović
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000, Zagreb, Croatia
| | - Iana Kalinina
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, 01307, Dresden, Germany
| | - Nenad Pavin
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10000, Zagreb, Croatia.
| | - Iva M Tolić
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, 01307, Dresden, Germany.
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000, Zagreb, Croatia.
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Tolić IM. Mitotic spindle: kinetochore fibers hold on tight to interpolar bundles. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2018; 47:191-203. [PMID: 28725997 PMCID: PMC5845649 DOI: 10.1007/s00249-017-1244-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 06/30/2017] [Accepted: 07/02/2017] [Indexed: 12/24/2022]
Abstract
When a cell starts to divide, it forms a spindle, a micro-machine made of microtubules, which separates the duplicated chromosomes. The attachment of microtubules to chromosomes is mediated by kinetochores, protein complexes on the chromosome. Spindle microtubules can be divided into three major classes: kinetochore microtubules, which form k-fibers ending at the kinetochore; interpolar microtubules, which extend from the opposite sides of the spindle and interact in the middle; and astral microtubules, which extend towards the cell cortex. Recent work in human cells has shown a close relationship between interpolar and kinetochore microtubules, where interpolar bundles are attached laterally to kinetochore fibers almost all along their length, acting as a bridge between sister k-fibers. Most of the interpolar bundles are attached to a pair of sister kinetochore fibers and vice versa. Thus, the spindle is made of modules consisting of a pair of sister kinetochore fibers and a bundle of interpolar microtubules that connects them. These interpolar bundles, termed bridging fibers, balance the forces acting at kinetochores and support the rounded shape of the spindle during metaphase. This review discusses the structure, function, and formation of kinetochore fibers and interpolar bundles, with an emphasis on how they interact. Their connections have an impact on the force balance in the spindle and on chromosome movement during mitosis because the forces in interpolar bundles are transmitted to kinetochore fibers and hence to kinetochores through these connections.
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Affiliation(s)
- Iva M Tolić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000, Zagreb, Croatia.
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Chacón MR, Delivani P, Tolić IM. Meiotic Nuclear Oscillations Are Necessary to Avoid Excessive Chromosome Associations. Cell Rep 2017; 17:1632-1645. [PMID: 27806301 DOI: 10.1016/j.celrep.2016.10.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 07/26/2016] [Accepted: 10/04/2016] [Indexed: 10/20/2022] Open
Abstract
Pairing of homologous chromosomes is a crucial step in meiosis, which in fission yeast depends on nuclear oscillations. However, how nuclear oscillations help pairing is unknown. Here, we show that homologous loci typically pair when the spindle pole body is at the cell pole and the nucleus is elongated, whereas they unpair when the spindle pole body is in the cell center and the nucleus is round. Inhibition of oscillations demonstrated that movement is required for initial pairing and that prolonged association of loci leads to mis-segregation. The double-strand break marker Rec25 accumulates in elongated nuclei, indicating that prolonged chromosome stretching triggers recombinatory pathways leading to mis-segregation. Mis-segregation is rescued by overexpression of the Holliday junction resolvase Mus81, suggesting that prolonged pairing results in irresolvable recombination intermediates. We conclude that nuclear oscillations exhibit a dual role, promoting initial pairing and restricting the time of chromosome associations to ensure proper segregation.
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Affiliation(s)
- Mariola R Chacón
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Petrina Delivani
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Iva M Tolić
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany; Ruđer Bošković Institute, Bijenička Cesta 54, 10000 Zagreb, Croatia.
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Blackwell R, Sweezy-Schindler O, Edelmaier C, Gergely ZR, Flynn PJ, Montes S, Crapo A, Doostan A, McIntosh JR, Glaser MA, Betterton MD. Contributions of Microtubule Dynamic Instability and Rotational Diffusion to Kinetochore Capture. Biophys J 2016; 112:552-563. [PMID: 27692365 DOI: 10.1016/j.bpj.2016.09.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 08/08/2016] [Accepted: 09/06/2016] [Indexed: 11/27/2022] Open
Abstract
Microtubule dynamic instability allows search and capture of kinetochores during spindle formation, an important process for accurate chromosome segregation during cell division. Recent work has found that microtubule rotational diffusion about minus-end attachment points contributes to kinetochore capture in fission yeast, but the relative contributions of dynamic instability and rotational diffusion are not well understood. We have developed a biophysical model of kinetochore capture in small fission-yeast nuclei using hybrid Brownian dynamics/kinetic Monte Carlo simulation techniques. With this model, we have studied the importance of dynamic instability and microtubule rotational diffusion for kinetochore capture, both to the lateral surface of a microtubule and at or near its end. Over a range of biologically relevant parameters, microtubule rotational diffusion decreased capture time, but made a relatively small contribution compared to dynamic instability. At most, rotational diffusion reduced capture time by 25%. Our results suggest that while microtubule rotational diffusion can speed up kinetochore capture, it is unlikely to be the dominant physical mechanism for typical conditions in fission yeast. In addition, we found that when microtubules undergo dynamic instability, lateral captures predominate even in the absence of rotational diffusion. Counterintuitively, adding rotational diffusion to a dynamic microtubule increases the probability of end-on capture.
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Affiliation(s)
- Robert Blackwell
- Department of Physics, University of Colorado, Boulder, Colorado
| | | | | | - Zachary R Gergely
- Department of Physics, University of Colorado, Boulder, Colorado; Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado
| | - Patrick J Flynn
- Department of Physics, University of Colorado, Boulder, Colorado
| | - Salvador Montes
- Department of Physics, University of Colorado, Boulder, Colorado
| | - Ammon Crapo
- Department of Physics, University of Colorado, Boulder, Colorado
| | - Alireza Doostan
- Department of Aerospace Engineering Sciences, University of Colorado, Boulder, Colorado
| | - J Richard McIntosh
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado
| | - Matthew A Glaser
- Department of Physics, University of Colorado, Boulder, Colorado
| | - Meredith D Betterton
- Department of Physics, University of Colorado, Boulder, Colorado; Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado.
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