title: Ect2/Pbl acts via Rho and polarity proteins to direct the assembly of an isotropic actomyosin cortex upon mitotic entry.
abstract: Entry into mitosis is accompanied by profound changes in cortical actomyosin organization. Here, we delineate a pathway downstream of the RhoGEF Pbl/Ect2 that directs this process in a model epithelium. Our data suggest that the release of Pbl/Ect2 from the nucleus at mitotic entry drives Rho-dependent activation of Myosin-II and, in parallel, induces a switch from Arp2/3 to Diaphanous-mediated cortical actin nucleation that depends on Cdc42, aPKC, and Par6. At the same time, the mitotic relocalization of these apical protein complexes to more lateral cell surfaces enables Cdc42/aPKC/Par6 to take on a mitosis-specific function-aiding the assembly of a relatively isotropic metaphase cortex. Together, these data reveal how the repolarization and remodeling of the actomyosin cortex are coordinated upon entry into mitosis to provide cells with the isotropic and rigid form they need to undergo faithful chromosome segregation and division in a crowded tissue environment.
authors.affiliation: MRC Laboratory of Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK; Graduate Program in Areas of Basic and Applied Biology (GABBA), University of Porto, 4200-465 Porto, Portugal.
authors.forename: André
authors.initials: A
authors.lastname: Rosa
authors.affiliation: MRC Laboratory of Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK.
authors.forename: Evi
authors.initials: E
authors.lastname: Vlassaks
authors.affiliation: MRC Laboratory of Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK.
authors.forename: Franck
authors.initials: F
authors.lastname: Pichaud
authors.affiliation: MRC Laboratory of Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK. Electronic address: b.baum@ucl.ac.uk.
authors.forename: Buzz
authors.initials: B
authors.lastname: Baum
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D051376:Actin-Related Protein 2-3 Complex / Q000378:metabolism*; D000205:Actomyosin / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D019204:GTP-Binding Proteins / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D047468:Immunoprecipitation; D008938:Mitosis / Q000502:physiology*; D011485:Protein Binding; D011493:Protein Kinase C / Q000378:metabolism*
chemical_list: D051376:Actin-Related Protein 2-3 Complex; C090145:Cdc42 protein, Drosophila; D029721:Drosophila Proteins; D020662:Guanine Nucleotide Exchange Factors; C121865:Pbl protein, Drosophila; D000205:Actomyosin; D011493:Protein Kinase C; D019204:GTP-Binding Proteins