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Mechanical Interactions in the Mitotic Spindle Machinery

English title Mechanical Interactions in the Mitotic Spindle Machinery
Applicant Telley Ivo Andreas
Number 136485
Funding scheme Fellowships for advanced researchers
Research institution Developmental Biology Unit European Molecular Biology Laboratory EMBL
Institution of higher education Institution abroad - IACH
Main discipline Biophysics
Start/End 01.08.2011 - 31.01.2012
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All Disciplines (3)

Discipline
Biophysics
Biochemistry
Cellular Biology, Cytology

Keywords (5)

mitosis; mitosis; mitotic spindle; micromechanics; microtubule

Lay Summary (German)

Lead
Die Mechanik der Teilung des genetischen Materials in einer Zelle.
Lay summary

Kontext: Die Zellteilung und die damit verbundene Teilung des Erbgutes (Genom) ist einer der bedeutendsten Prozesse in unserer Natur. Sie gewährleistet die Differenzierung und das Wachstum aller Lebewesen. Dabei werden Erbgut und andere wichtige Elemente der Zelle verdoppelt und den Tochterzellen zugeordnet. Vor der tatsächlichen Spaltung der Zelle kommt es zur Kernteilung, der sogenannten ‚Mitose'. Dabei werden die replizierten Chromosomen räumlich aufgereiht und voneinander getrennt und auseinander gezogen. Dieser Prozess wird durch die sogenannte mitotische Spindel erreicht, eine molekulare Superstruktur bestehend aus Mikrotubuli, einem Biopolymer, sowie assoziierten molekularen Maschinen (Motorproteine), und deren Regulatoren und anderen Bindeproteinen. Die für die Chromosomentrennung verantwortlichen Kräfte und die räumliche und zeitliche Koordination sind nicht vollständig verstanden und deshalb ein aktuelles Thema in der Grundlagenforschung. Es ist zum Beispiel nicht klar, an welcher Stelle der Spindel diese Kräfte entstehen, an den sogenannten Spindelpolen oder an den Verbindungspunkten zwischen Chromosomen und Spindel. Methoden: Es sollen Methoden entwickelt werden, mit denen die Mechanik der mitotischen Spindel im Detail studiert werden kann. Die Entwicklung einer Apparatur zur Messung von Kräften, zur mechanischen Charakterisierung der Spindel sowie deren Teilkomponenten ist notwendig. Dazu werden etablierte Methoden der Lichtmikroskopie, der Oberflächentechnik und der Nanotechnik verwendet. Grundlegende Methoden der Biochemie werden zu Hilfe gezogen. Bedeutung: Die Grundlagenforschung im Bereich der Zellteilung hat direkte Anwendungen in der Krebsforschung. Da die Proliferation von Krebszellen erhöht ist, was mit schnellem Gewebewachstum einhergeht, werden Wege gesucht, um diese schnelle Zellteilungsfolge zu hemmen oder zu unterbinden. Dies bedarf jedoch detaillierter Kenntnisse über die Schlüsselkomponenten und Regulatoren. Ein Ansatz ist die Hemmung der Kraft generierenden Proteine.

Direct link to Lay Summary Last update: 13.02.2013

Responsible applicant and co-applicants

Publications

Publication
A single Drosophila embryo extract for the study of mitosis ex vivo
Telley Ivo A., Gáspár Imre, Ephrussi Anne, Surrey Thomas (2013), A single Drosophila embryo extract for the study of mitosis ex vivo, in Nature Protocols, 8(2), 310-324.
Aster migration determines the length scale of nuclear separation in the Drosophila syncytial embryo.
Telley Ivo A, Gáspár Imre, Ephrussi Anne, Surrey Thomas (2012), Aster migration determines the length scale of nuclear separation in the Drosophila syncytial embryo., in The Journal of cell biology, 197(7), 887-95.

Collaboration

Group / person Country
Types of collaboration
Anne Ephrussi / EMBL Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
American Society of Cell Biology, Annual Meeting Talk given at a conference Nuclear divisions under space constraints studied in single embryo extract. 04.12.2011 Denver, CO, United States of America Telley Ivo Andreas;


Associated projects

Number Title Start Funding scheme
126255 Mechanical Interactions in the Mitotic Spindle Machinery 01.08.2009 Fellowships for advanced researchers

Abstract

In one of the central processes in the life cycle of every organism, a process known as mitosis, a cell is physically divided into two genetically identical daughter cells. In eukaryotes the replicated chromosomes are divided by a structure called the mitotic spindle. The mechanical determinants responsible for chromosome segregation are thought to be the polymerisation properties of microtubules and the microtubule-based molecular motors. Cytoplasmic dynein and members of different kinesin families have been found to be essential players in spindle assembly. For example, depletion of kinesin-5 prevents correct spindle assembly. Overexpression of kinesin-14 has been shown to change spindle length. These two motors with opposite directionality of movement have been proposed to antagonize each other. On the other hand, static microtubule cross-linkers are activated in anaphase where they localize in the middle of the spindle where antiparallel microtubules overlap. It is also believed that forces and the overall stiffness of the spindle are especially high in this phase due to the segregation of the chromosomes. However, how these components and activities work as an integrative machine has not yet been determined experimentally. What is also unclear in quite general terms is how the mechanical properties of the spindle change throughout the different phases, especially the late phases, of mitosis. So far, the understanding of the mechanics of mitosis is based on the interpretation of inhibition experiments in cells and single molecule studies of the involved motors in vitro.In my original proposal I outlined a study designed to address this important gap in our understanding of spindle formation and stability. In the past year I have studied different motors/microtubule cross-linkers interacting with microtubules in vitro. The implementation of force measurements on a configuration with two overlapping microtubules has proven difficult with many non-trivial technical problems. Additionally, I have proposed to mechanically perturb the mitotic spindle and to measure changes in motor distribution upon load. The overall goal of the proposed work is to characterize the load-dependent kinetics of different key players in a physiologically relevant environment. Recently, I have established a novel experimental setup based on the extraction of cytoplasm from individual early-stage Drosophila embryos. I could show that the extraction procedure fully preserves the functionality of the extract, including the rapid nuclear cycling and the stereotypical processes of mitosis. The biochemical and mechanical accessibility of the spindle structures in this assay make it ideal for performing mechanical experiments using micro- or nano-tools (as I proposed) or using microfluidics techniques (as I recently implemented).
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