title: Drosophila nonmuscle myosin II promotes the asymmetric segregation of cell fate determinants by cortical exclusion rather than active transport.
abstract: Cell fate diversity can be achieved through the asymmetric segregation of cell fate determinants. In the Drosophila embryo, neuroblasts divide asymmetrically and in a stem cell fashion. The determinants Prospero and Numb localize in a basal crescent and are partitioned from neuroblasts to their daughters (GMCs). Here we show that nonmuscle myosin II regulates asymmetric cell division by an unexpected mechanism, excluding determinants from the apical cortex. Myosin II is activated by Rho kinase and restricted to the apical cortex by the tumor suppressor Lethal (2) giant larvae. During prophase and metaphase, myosin II prevents determinants from localizing apically. At anaphase and telophase, myosin II moves to the cleavage furrow and appears to "push" rather than carry determinants into the GMC. Therefore, the movement of myosin II to the contractile ring not only initiates cytokinesis but also completes the partitioning of cell fate determinants from the neuroblast to its daughter.
authors.affiliation: Wellcome Trust/Cancer Research UK Institute and Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, United Kingdom.
authors.forename: Claudia S
authors.initials: CS
authors.lastname: Barros
authors.forename: Chris B
authors.initials: CB
authors.lastname: Phelps
authors.forename: Andrea H
authors.initials: AH
authors.lastname: Brand
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001693:Biological Transport, Active / Q000502:physiology; D018797:Cell Cycle Proteins / Q000378:metabolism; D019070:Cell Lineage / Q000502:physiology; D016764:Cell Polarity / Q000502:physiology; D004330:Drosophila / Q000196:embryology*; D029721:Drosophila Proteins / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D024462:Myosin Type II / Q000235:genetics* / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D008941:Spindle Apparatus / Q000502:physiology; D013234:Stem Cells / Q000166:cytology / Q000502:physiology*; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D054460:rho-Associated Kinases
chemical_list: D018797:Cell Cycle Proteins; D029721:Drosophila Proteins; D047908:Intracellular Signaling Peptides and Proteins; C107613:Mira protein, Drosophila; D025521:Tumor Suppressor Proteins; C081435:l(2)gl protein, Drosophila; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D024462:Myosin Type II