title: Ensconsin/Map7 promotes microtubule growth and centrosome separation in Drosophila neural stem cells.
abstract: The mitotic spindle is crucial to achieve segregation of sister chromatids. To identify new mitotic spindle assembly regulators, we isolated 855 microtubule-associated proteins (MAPs) from Drosophila melanogaster mitotic or interphasic embryos. Using RNAi, we screened 96 poorly characterized genes in the Drosophila central nervous system to establish their possible role during spindle assembly. We found that Ensconsin/MAP7 mutant neuroblasts display shorter metaphase spindles, a defect caused by a reduced microtubule polymerization rate and enhanced by centrosome ablation. In agreement with a direct effect in regulating spindle length, Ensconsin overexpression triggered an increase in spindle length in S2 cells, whereas purified Ensconsin stimulated microtubule polymerization in vitro. Interestingly, ensc-null mutant flies also display defective centrosome separation and positioning during interphase, a phenotype also detected in kinesin-1 mutants. Collectively, our results suggest that Ensconsin cooperates with its binding partner Kinesin-1 during interphase to trigger centrosome separation. In addition, Ensconsin promotes microtubule polymerization during mitosis to control spindle length independent of Kinesin-1.
authors.affiliation: Cytoskeleton and Cell Proliferation, 2 Tubulin and Interacting Proteins, and 3 Spatio-temporal Regulation of Transcription, Biosit, Université de Rennes I, Centre National de la Recherche Scientifique, UMR 6290, 35043 Rennes, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Gallaud
authors.forename: Renaud
authors.initials: R
authors.lastname: Caous
authors.forename: Aude
authors.initials: A
authors.lastname: Pascal
authors.forename: Franck
authors.initials: F
authors.lastname: Bazile
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Gagné
authors.forename: Sébastien
authors.initials: S
authors.lastname: Huet
authors.forename: Guy G
authors.initials: GG
authors.lastname: Poirier
authors.forename: Denis
authors.initials: D
authors.lastname: Chrétien
authors.forename: Laurent
authors.initials: L
authors.lastname: Richard-Parpaillon
authors.forename: Régis
authors.initials: R
authors.lastname: Giet
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D018385:Centrosome / Q000378:metabolism*; D020090:Chromosome Segregation; D029721:Drosophila Proteins / Q000378:metabolism; D004331:Drosophila melanogaster / Q000166:cytology*; D007399:Interphase; D016547:Kinesins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000502:physiology*; D008870:Microtubules / Q000378:metabolism*; D008938:Mitosis; D058953:Neural Stem Cells / Q000502:physiology*; D055503:Protein Multimerization; D008941:Spindle Apparatus / Q000378:metabolism; D059008:Time-Lapse Imaging
chemical_list: D029721:Drosophila Proteins; D008869:Microtubule-Associated Proteins; C515209:Khc protein, Drosophila; D016547:Kinesins