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Klemm AH, Bosilj A, Gluncˇic M, Pavin N, Tolic IM. Metaphase kinetochore movements are regulated by kinesin-8 motors and microtubule dynamic instability. Mol Biol Cell 2018; 29:1332-1345. [PMID: 29851559 PMCID: PMC5994901 DOI: 10.1091/mbc.e17-11-0667] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
During metaphase, sister chromatids are connected to microtubules extending from the opposite spindle poles via kinetochores to protein complexes on the chromosome. Kinetochores congress to the equatorial plane of the spindle and oscillate around it, with kinesin-8 motors restricting these movements. Yet, the physical mechanism underlying kinetochore movements is unclear. We show that kinetochore movements in the fission yeast Schizosaccharomyces pombe are regulated by kinesin-8-promoted microtubule catastrophe, force-induced rescue, and microtubule dynamic instability. A candidate screen showed that among the selected motors only kinesin-8 motors Klp5/Klp6 are required for kinetochore centering. Kinesin-8 accumulates at the end of microtubules, where it promotes catastrophe. Laser ablation of the spindle resulted in kinetochore movement toward the intact spindle pole in wild-type and klp5Δ cells, suggesting that kinetochore movement is driven by pulling forces. Our theoretical model with Langevin description of microtubule dynamic instability shows that kinesin-8 motors are required for kinetochore centering, whereas sensitivity of rescue to force is necessary for the generation of oscillations. We found that irregular kinetochore movements occur for a broader range of parameters than regular oscillations. Thus, our work provides an explanation for how regulation of microtubule dynamic instability contributes to kinetochore congression and the accompanying movements around the spindle center.
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Affiliation(s)
- Anna H Klemm
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Agneza Bosilj
- Department of Physics, Faculty of Science, University of Zagreb, 10000 Zagreb, Croatia
| | - Matko Gluncˇic
- Department of Physics, Faculty of Science, University of Zagreb, 10000 Zagreb, Croatia
| | - Nenad Pavin
- Department of Physics, Faculty of Science, University of Zagreb, 10000 Zagreb, Croatia
| | - Iva M Tolic
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany.,Division of Molecular Biology, Rud¯er Boškovic´ Institute, 10000 Zagreb, Croatia
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Milas A, Jagrić M, Martinčić J, Tolić IM. Optogenetic reversible knocksideways, laser ablation, and photoactivation on the mitotic spindle in human cells. Methods Cell Biol 2018; 145:191-215. [DOI: 10.1016/bs.mcb.2018.03.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Buđa R, Vukušić K, Tolić IM. Dissection and characterization of microtubule bundles in the mitotic spindle using femtosecond laser ablation. Methods Cell Biol 2017; 139:81-101. [PMID: 28215341 DOI: 10.1016/bs.mcb.2016.11.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The mitotic spindle is a highly organized and dynamic structure required for segregation of the genetic material into two daughter cells. Although most of the individual players involved in building the spindle have been characterized in vitro, a general understanding of how all of the spindle players act together in vivo is still missing. Hence, in recent years, experiments have focused on introducing mechanical perturbations of the spindle on a micron scale, thereby providing insight into its function and organization, as well as into forces acting in the spindle. Among different types of mechanical perturbations, optical ones are more flexible, less invasive, and more precise than other approaches. In this chapter, we describe a detailed protocol for cutting the microtubule bundles in human cells using a near-infrared femtosecond laser. This type of laser microsurgery provides the ability to precisely sever a single microtubule bundle while preserving spindle integrity and dynamics. Furthermore, we describe quantitative measurements obtained from the response of a severed microtubule bundle to laser ablation, which reveal the structure and function of individual parts of the spindle, such as the bridging fiber connecting sister k-fibers. Finally, the method described here can be easily combined with other quantitative techniques to address the complexity of the spindle.
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Affiliation(s)
- R Buđa
- Ruđer Bošković Institute, Zagreb, Croatia
| | - K Vukušić
- Ruđer Bošković Institute, Zagreb, Croatia
| | - I M Tolić
- Ruđer Bošković Institute, Zagreb, Croatia
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Cojoc G, Roscioli E, Zhang L, García-Ulloa A, Shah JV, Berns MW, Pavin N, Cimini D, Tolić IM, Gregan J. Laser microsurgery reveals conserved viscoelastic behavior of the kinetochore. J Cell Biol 2016; 212:767-76. [PMID: 27002163 PMCID: PMC4810299 DOI: 10.1083/jcb.201506011] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 02/25/2016] [Indexed: 11/29/2022] Open
Abstract
Accurate chromosome segregation depends on proper kinetochore-microtubule attachment. Upon microtubule interaction, kinetochores are subjected to forces generated by the microtubules. In this work, we used laser ablation to sever microtubules attached to a merotelic kinetochore, which is laterally stretched by opposing pulling forces exerted by microtubules, and inferred the mechanical response of the kinetochore from its length change. In both mammalian PtK1 cells and in the fission yeast Schizosaccharomyces pombe, kinetochores shortened after microtubule severing. Interestingly, the inner kinetochore-centromere relaxed faster than the outer kinetochore. Whereas in fission yeast all kinetochores relaxed to a similar length, in PtK1 cells the more stretched kinetochores remained more stretched. Simple models suggest that these differences arise because the mechanical structure of the mammalian kinetochore is more complex. Our study establishes merotelic kinetochores as an experimental model for studying the mechanical response of the kinetochore in live cells and reveals a viscoelastic behavior of the kinetochore that is conserved in yeast and mammalian cells.
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Affiliation(s)
- Gheorghe Cojoc
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Emanuele Roscioli
- Department of Biological Sciences and Biocomplexity Institute, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
| | - Lijuan Zhang
- Max F. Perutz Laboratories, Department of Chromosome Biology, University of Vienna, 1030 Vienna, Austria
| | - Alfonso García-Ulloa
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Jagesh V Shah
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115
| | - Michael W Berns
- Beckman Laser Institute and University of California, Irvine, Irvine, CA 92612
| | - Nenad Pavin
- Department of Physics, Faculty of Science, University of Zagreb, 10000 Zagreb, Croatia
| | - Daniela Cimini
- Department of Biological Sciences and Biocomplexity Institute, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
| | - Iva M Tolić
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany Division of Molecular Biology, Ruđer Bošković Institute, 10000 Zagreb, Croatia
| | - Juraj Gregan
- Max F. Perutz Laboratories, Department of Chromosome Biology, University of Vienna, 1030 Vienna, Austria
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Glunčić M, Maghelli N, Krull A, Krstić V, Ramunno-Johnson D, Pavin N, Tolić IM. Kinesin-8 motors improve nuclear centering by promoting microtubule catastrophe. PHYSICAL REVIEW LETTERS 2015; 114:078103. [PMID: 25763975 DOI: 10.1103/physrevlett.114.078103] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Indexed: 06/04/2023]
Abstract
In fission yeast, microtubules push against the cell edge, thereby positioning the nucleus in the cell center. Kinesin-8 motors regulate microtubule catastrophe; however, their role in nuclear positioning is not known. Here we develop a physical model that describes how kinesin-8 motors affect nuclear centering by promoting a microtubule catastrophe. Our model predicts the improved centering of the nucleus in the presence of motors, which we confirmed experimentally in living cells. The model also predicts a characteristic time for the recentering of a displaced nucleus, which is supported by our experiments where we displaced the nucleus using optical tweezers.
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Affiliation(s)
- Matko Glunčić
- Department of Physics, Faculty of Science, University of Zagreb, 10000 Zagreb, Croatia
| | - Nicola Maghelli
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Alexander Krull
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Vladimir Krstić
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
| | | | - Nenad Pavin
- Department of Physics, Faculty of Science, University of Zagreb, 10000 Zagreb, Croatia
- Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
| | - Iva M Tolić
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
- Division of Molecular Biology, Ruđer Bošković Institute, 10000 Zagreb, Croatia
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Guarino E, Cojoc G, García-Ulloa A, Tolić IM, Kearsey SE. Real-time imaging of DNA damage in yeast cells using ultra-short near-infrared pulsed laser irradiation. PLoS One 2014; 9:e113325. [PMID: 25409521 PMCID: PMC4237433 DOI: 10.1371/journal.pone.0113325] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 10/22/2014] [Indexed: 01/12/2023] Open
Abstract
Analysis of accumulation of repair and checkpoint proteins at repair sites in yeast nuclei has conventionally used chemical agents, ionizing radiation or induction of endonucleases to inflict localized damage. In addition to these methods, similar studies in mammalian cells have used laser irradiation, which has the advantage that damage is inflicted at a specific nuclear region and at a precise time, and this allows accurate kinetic analysis of protein accumulation at DNA damage sites. We show here that it is feasible to use short pulses of near-infrared laser irradiation to inflict DNA damage in subnuclear regions of yeast nuclei by multiphoton absorption. In conjunction with use of fluorescently-tagged proteins, this allows quantitative analysis of protein accumulation at damage sites within seconds of damage induction. PCNA accumulated at damage sites rapidly, such that maximum accumulation was seen approximately 50 s after damage, then levels declined linearly over 200-1000 s after irradiation. RPA accumulated with slower kinetics such that hardly any accumulation was detected within 60 s of irradiation, and levels subsequently increased linearly over the next 900 s, after which levels were approximately constant (up to ca. 2700 s) at the damage site. This approach complements existing methodologies to allow analysis of key damage sensors and chromatin modification changes occurring within seconds of damage inception.
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Affiliation(s)
- Estrella Guarino
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Gheorghe Cojoc
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | | | - Iva M. Tolić
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Stephen E. Kearsey
- Department of Zoology, University of Oxford, Oxford, United Kingdom
- * E-mail:
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Cecala C, Rubakhin SS, Mitchell JW, Gillette MU, Sweedler JV. A hyphenated optical trap capillary electrophoresis laser induced native fluorescence system for single-cell chemical analysis. Analyst 2012; 137:2965-72. [PMID: 22543409 PMCID: PMC3558031 DOI: 10.1039/c2an35198f] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Single-cell measurements allow a unique glimpse into cell-to-cell heterogeneity; even small changes in selected cells can have a profound impact on an organism's physiology. Here an integrated approach to single-cell chemical sampling and assay are described. Capillary electrophoresis (CE) with laser-induced native fluorescence (LINF) has the sensitivity to characterize natively fluorescent indoles and catechols within individual cells. While the separation and detection approaches are well established, the sampling and injection of individually selected cells requires new approaches. We describe an optimized system that interfaces a single-beam optical trap with CE and multichannel LINF detection. A cell is localized within the trap and then the capillary inlet is positioned near the cell using a computer-controlled micromanipulator. Hydrodynamic injection allows cell lysis to occur within the capillary inlet, followed by the CE separation and LINF detection. The use of multiple emission wavelengths allows improved analyte identification based on differences in analyte fluorescence emission profiles and migration time. The system enables injections of individual rat pinealocytes and quantification of their endogenous indoles, including serotonin, N-acetyl-serotonin, 5-hydroxyindole-3-acetic acid, tryptophol and others. The amounts detected in individual cells incubated in 5-hydroxytryptophan ranged from 10(-14) mol to 10(-16) mol, an order of magnitude higher than observed in untreated pinealocytes.
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Affiliation(s)
- Christine Cecala
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Stanislav S. Rubakhin
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Jennifer W. Mitchell
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Martha U. Gillette
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Jonathan V. Sweedler
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL 61801
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Abstract
Cells are extraordinarily complex, containing thousands of different analytes with concentrations spanning at least nine orders of magnitude. Analyzing single cells instead of tissue homogenates provides unique insights into cell-to-cell heterogeneity and aids in distinguishing normal cells from pathological ones. The high sensitivity and low sample consumption of capillary and on-chip electrophoresis, when integrated with fluorescence, electrochemical, and mass spectrometric detection methods, offer an ideal toolset for examining single cells and even subcellular organelles; however, the isolation and loading of such small samples into these devices is challenging. Recent advances have addressed this issue by interfacing a variety of enhanced mechanical, microfluidic, and optical sampling techniques to capillary and on-chip electrophoresis instruments for single-cell analyses.
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Affiliation(s)
- Christine Cecala
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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