Wac: a new Augmin subunit required for chromosome alignment but not for acentrosomal microtubule assembly in female meiosis |
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Authors: | Ana M Meireles Katherine H Fisher Nathalie Colombié James G Wakefield Hiroyuki Ohkura |
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Institution: | 1.Wellcome Trust Centre for Cell Biology, The University of Edinburgh, Edinburgh, Scotland EH9 3JR, UK;2.Life Sciences Interface Doctoral Training Centre and Department of Zoology, University of Oxford, Oxford OX1 3PJ, England, UK;3.Doctoral Programme in Experimental Biology and Biomedicine, Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra 3004-157, Portugal |
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Abstract: | The bipolar spindle forms without centrosomes naturally in female meiosis and by experimental manipulation in mitosis. Augmin is a recently discovered protein complex required for centrosome-independent microtubule generation within the spindle in Drosophila
melanogaster cultured cells. Five subunits of Augmin have been identified so far, but neither their organization within the complex nor their role in developing organisms is known. In this study, we report a new Augmin subunit, wee Augmin component (Wac). Wac directly interacts with another Augmin subunit, Dgt2, via its coiled-coil domain. Wac depletion in cultured cells, especially without functional centrosomes, causes severe defects in spindle assembly. We found that a wac deletion mutant is viable but female sterile and shows only a mild impact on somatic mitosis. Unexpectedly, mutant female meiosis showed robust microtubule assembly of the acentrosomal spindle but frequent chromosome misalignment. For the first time, this study establishes the role of an Augmin subunit in developing organisms and provides an insight into the architecture of the complex. |
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