Analysis of mitotic and post-mitotic functions of Spindly in Drosophila melanogaster

  • Giuliana Clemente

    Student thesis: Doctoral ThesisDoctor of Philosophy


    The gene spindly encodes for a coiled-coil containing protein required for the successful completion of mitosis and yet undefined activity in the control of cytoskeleton remodelling in post-mitotic cells. This research project aims to elucidate the requirement for Drosophila Spindly in both scenarios, mitosis and interphase. To address this question, loss- and gain-of-function experiments were performed to screen the effects of both downregulation and overexpression of Spindly, in a variety of cellular and developmental backgrounds. Drosophila is an elegible system for this analysis since it is highly genetically tractable and provides a well-characterised model for cell migration and cell division.
    We found that loss of Spindly disrupts normal embryonic development resulting in a deregulation of cytoskeletal components as well as an alteration of centrosome biology. A proteomic approach based on affinity-purified mass spectrometry experiments was undertaken to identify novel binding partners for Spindly and narrow down the molecular pathway(s) in which Spindly activity may be required during develpment. MS data support its potential interaction with known regulators of centrosome biology and mitotic spindle activity, corroborating our phenotypic observations.
    Similarly, the overexpression of a GFP-tagged version of the protein affects embryonic development. Increased levels of Spindly above the wild-type threshold resulted in reduced embryo survival and in altered egg morphology, pointing to a potential function for this factor in egg elongation.
    To investigate the role of Spindly in post-mitotic cells and to unravel additional, uncharacterised function(s) of this protein during interphase, cells were examined for abnormalities in cell migration upon either Spindly depletion or overexpression. Downregulation of Spindly causes border cells to move sooner or faster through the egg chamber. Conversely, upregulation delays the migration of these cells towards the oocyte and in addition causes severe morphological alterations of the cluster.
    In summary, Spindly has a major role in the control of cell division, mainly via co-ordination of cytoskeleton components during mitosis. Additionally, this study shows for the first time a role for Spindly in post-mitotic cells, namely border cell migration. This system therefore provides a basis for functional dissection of Spindly function in cell migration.
    Date of Award2015
    Original languageEnglish
    SponsorsCancer Research UK
    SupervisorHans-Arno Muller (Supervisor)

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