title: γ-Tubulin Ring Complexes and EB1 play antagonistic roles in microtubule dynamics and spindle positioning.
abstract: γ-Tubulin is critical for microtubule (MT) assembly and organization. In metazoa, this protein acts in multiprotein complexes called γ-Tubulin Ring Complexes (γ-TuRCs). While the subunits that constitute γ-Tubulin Small Complexes (γ-TuSCs), the core of the MT nucleation machinery, are essential, mutation of γ-TuRC-specific proteins in Drosophila causes sterility and morphological abnormalities via hitherto unidentified mechanisms. Here, we demonstrate a role of γ-TuRCs in controlling spindle orientation independent of MT nucleation activity, both in cultured cells and in vivo, and examine a potential function for γ-TuRCs on astral MTs. γ-TuRCs locate along the length of astral MTs, and depletion of γ-TuRC-specific proteins increases MT dynamics and causes the plus-end tracking protein EB1 to redistribute along MTs. Moreover, suppression of MT dynamics through drug treatment or EB1 down-regulation rescues spindle orientation defects induced by γ-TuRC depletion. Therefore, we propose a role for γ-TuRCs in regulating spindle positioning by controlling the stability of astral MTs.
authors.affiliation: Centre Biologie du Développement, UMR 5547 CNRS-UPS Toulouse 3, Toulouse Cedex 04, France.
authors.forename: Anaïs
authors.initials: A
authors.lastname: Bouissou
authors.forename: Christel
authors.initials: C
authors.lastname: Vérollet
authors.forename: Hélène
authors.initials: H
authors.lastname: de Forges
authors.forename: Laurence
authors.initials: L
authors.lastname: Haren
authors.forename: Yohanns
authors.initials: Y
authors.lastname: Bellaïche
authors.forename: Franck
authors.initials: F
authors.lastname: Perez
authors.forename: Andreas
authors.initials: A
authors.lastname: Merdes
authors.forename: Brigitte
authors.initials: B
authors.lastname: Raynaud-Messina
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D002478:Cells, Cultured; D004330:Drosophila; D006367:HeLa Cells; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000502:physiology*; D008870:Microtubules / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000502:physiology; D008941:Spindle Apparatus / Q000502:physiology*; D014404:Tubulin / Q000502:physiology*
chemical_list: C405804:EB1 microtubule binding proteins; D008869:Microtubule-Associated Proteins; D046912:Multiprotein Complexes; D014404:Tubulin