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Dryad

Data from: Augmin prevents merotelic attachments by promoting proper arrangement of bridging and kinetochore fibers

Cite this dataset

Štimac, Valentina et al. (2022). Data from: Augmin prevents merotelic attachments by promoting proper arrangement of bridging and kinetochore fibers [Dataset]. Dryad. https://doi.org/10.5061/dryad.fn2z34tz7

Abstract

The human mitotic spindle is made of microtubules nucleated at centrosomes, at kinetochores, and from pre-existing microtubules by the augmin complex. However, it is unknown how the augmin-mediated nucleation affects distinct microtubule classes and thereby mitotic fidelity. Here we use superresolution microscopy to analyze the previously indistinguishable microtubule arrangements within the crowded metaphase plate area and demonstrate that augmin is vital for the formation of uniformly arranged parallel units consisting of sister kinetochore fibers connected by a bridging fiber. This ordered geometry helps both prevent and resolve merotelic attachments. Whereas augmin-nucleated bridging fibers prevent merotelic attachments by creating a nearly parallel and highly bundled microtubule arrangement unfavorable for creating additional attachments, augmin-nucleated k-fibers produce robust force required to resolve errors during anaphase. STED microscopy revealed that bridging fibers were impaired twice as much as k-fibers following augmin depletion. The complete absence of bridging fibers from a significant portion of kinetochore pairs, especially in the inner part of the spindle, resulted in the specific reduction of the interkinetochore distance. Taken together, we propose a model where augmin promotes mitotic fidelity by generating assemblies consisting of bridging and kinetochore fibers that align sister kinetochores to face opposite poles, thereby preventing erroneous attachments.

Funding

Croatian Science Foundation Cooperation Programme with Croatian Scientists in Diaspora “Research Cooperability” , Award: PZS-2019-02-7653

European Research Council, Award: 647077

European Research Council, Award: 855158

Croatian Government and European Union through the European Regional Development Fund - the Competitiveness and Cohesion Operational Programme, Award: KK.01.1.1.01.0004

Croatian Government and European Union through the European Regional Development Fund - the Competitiveness and Cohesion Operational Programme, Award: KK.01.1.1.04.0057