title: Progenitor properties of symmetrically dividing Drosophila neuroblasts during embryonic and larval development.
abstract: Asymmetric cell division generates two daughter cells of differential gene expression and/or cell shape. Drosophila neuroblasts undergo typical asymmetric divisions with regard to both features; this is achieved by asymmetric segregation of cell fate determinants (such as Prospero) and also by asymmetric spindle formation. The loss of genes involved in these individual asymmetric processes has revealed the roles of each asymmetric feature in neurogenesis, yet little is known about the fate of the neuroblast progeny when asymmetric processes are blocked and the cells divide symmetrically. We genetically created such neuroblasts, and found that in embryos, they were initially mitotic and then gradually differentiated into neurons, frequently forming a clone of cells homogeneous in temporal identity. By contrast, larval neuroblasts with the same genotype continued to proliferate without differentiation. Our results indicate that asymmetric divisions govern lineage length and progeny fate, consequently generating neural diversity, while the progeny fate of symmetrically dividing neuroblasts depends on developmental stages, presumably reflecting differential activities of Prospero in the nucleus.
authors.affiliation: Laboratory for Cell Asymmetry, RIKEN Center for Developmental Biology, 2-2-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kitajima
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Fuse
authors.forename: Takako
authors.initials: T
authors.lastname: Isshiki
authors.forename: Fumio
authors.initials: F
authors.lastname: Matsuzaki
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002455:Cell Division; D049109:Cell Proliferation; D029721:Drosophila Proteins / Q000378:metabolism; D004331:Drosophila melanogaster / Q000166:cytology* / Q000196:embryology* / Q000235:genetics; D047108:Embryonic Development; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect / Q000235:genetics; D007814:Larva / Q000166:cytology / Q000254:growth & development; D008954:Models, Biological; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D050505:Mutant Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C073099:pros protein, Drosophila; C070350:dlg1 protein, Drosophila