γ‐Tubulin Ring Complexes and EB1 play antagonistic roles in microtubule dynamics and spindle positioning |
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Authors: | Ana?s Bouissou Christel Vérollet Hélène de Forges Laurence Haren Yohanns Bella?che Franck Perez Andreas Merdes Brigitte Raynaud‐Messina |
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Affiliation: | 1. Centre Biologie du Développement, UMR 5547, CNRS‐UPS Toulouse 3, Toulouse Cedex 04, France;2. Institut de Pharmacologie et de Biologie Structurale, UMR 5089, Toulouse Cedex 04, France;3. Institut Curie, CNRS UMR144, Paris Cedex 05, France;4. Institut Curie, CNRS UMR 3215‐INSERM U934, Paris Cedex 05, France |
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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. |
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Keywords: | gamma‐tubulin complexes microtubule dynamics mitosis spindle orientation |
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