title: The sequential activation of the mitotic microtubule assembly pathways favors bipolar spindle formation.
abstract: Centrosome maturation is the process by which the duplicated centrosomes recruit pericentriolar components and increase their microtubule nucleation activity before mitosis. The role of this process in cells entering mitosis has been mostly related to the separation of the duplicated centrosomes and thereby to the assembly of a bipolar spindle. However, spindles can form without centrosomes. In fact, all cells, whether they have centrosomes or not, rely on chromatin-driven microtubule assembly to form a spindle. To test whether the sequential activation of these microtubule assembly pathways, defined by centrosome maturation and nuclear envelope breakdown, plays any role in spindle assembly, we combined experiments in tissue culture cells and Xenopus laevis egg extracts with a mathematical model. We found that interfering with the sequential activation of the microtubule assembly pathways compromises bipolar spindle assembly in tissue culture cells but not in X. laevis egg extracts. Our data suggest a novel function for centrosome maturation that determines the contribution of the chromosomal microtubule assembly pathway and favors bipolar spindle formation in most animal cells in which tubulin is in limiting amounts.
authors.affiliation: Cell and Developmental Biology Programme, Centre for Genomic Regulation, Barcelona Institute of Science and Technology, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08003 Barcelona, Spain.
authors.forename: Tommaso
authors.initials: T
authors.lastname: Cavazza
authors.affiliation: Departament de Fisica Fonamental, Universitat de Barcelona, 08028 Barcelona, Spain Max-Planck-Institut für Intelligente Systeme and IV. Institut für Theoretische Physik, Universität Stuttgart, D-70569 Stuttgart, Germany.
authors.forename: Paolo
authors.initials: P
authors.lastname: Malgaretti
authors.affiliation: Cell and Developmental Biology Programme, Centre for Genomic Regulation, Barcelona Institute of Science and Technology, 08003 Barcelona, Spain Universitat Pompeu Fabra, 08003 Barcelona, Spain Institució Catalana de Recerca I Estudis Avançats, 08010 Barcelona, Spain isabelle.vernos@crg.es.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Vernos
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques; D002453:Cell Cycle; D018385:Centrosome / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism* / Q000502:physiology; D008938:Mitosis; D008962:Models, Theoretical; D008941:Spindle Apparatus / Q000378:metabolism* / Q000502:physiology; D064047:Spindle Poles; D014404:Tubulin / Q000378:metabolism; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000378:metabolism
chemical_list: D002843:Chromatin; D014404:Tubulin; D029867:Xenopus Proteins