title: The conserved discs-large binding partner Banderuola regulates asymmetric cell division in Drosophila.
abstract: BACKGROUND
  Asymmetric cell division (ACD) is a key process that allows different cell types to be generated at precisely defined times and positions. In Drosophila, neural precursor cells rely heavily on ACD to generate the different cell types in the nervous system. A conserved protein machinery that regulates ACD has been identified in Drosophila, but how this machinery acts to allow the establishment of differential cell fates is not entirely understood.
  
  
  RESULTS
  To identify additional proteins required for ACD, we have carried out an in vivo live imaging RNAi screen for genes affecting the asymmetric segregation of Numb in Drosophila sensory organ precursor cells. We identify Banderuola (Bnd), an essential regulator of cell polarization, spindle orientation, and asymmetric protein localization in Drosophila neural precursor cells. Genetic and biochemical experiments show that Bnd acts together with the membrane-associated tumor suppressor Discs-large (Dlg) to establish antagonistic cortical domains during ACD. Inhibiting Bnd strongly enhances the dlg phenotype, causing massive brain tumors upon knockdown of both genes. Because the mammalian homologs of Bnd and Dlg are interacting as well, Bnd function might be conserved in vertebrates, and it might also regulate cell polarity in higher organisms.
  
  
  CONCLUSIONS
  Bnd is a novel regulator of ACD in different types of cells. Our data place Bnd at the top of the hierarchy of the factors involved in ACD, suggesting that its main function is to mediate the localization and function of the Dlg tumor suppressor. Bnd has an antioncogenic function that is redundant with Dlg, and the physical interaction between the two proteins is conserved in evolution.
authors.affiliation: Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna 1030, Austria.
authors.forename: Federico
authors.initials: F
authors.lastname: Mauri
authors.affiliation: Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna 1030, Austria.
authors.forename: Ilka
authors.initials: I
authors.lastname: Reichardt
authors.affiliation: Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna 1030, Austria.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Mummery-Widmer
authors.affiliation: Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna 1030, Austria.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Yamazaki
authors.affiliation: Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna 1030, Austria. Electronic address: juergen.knoblich@imba.oeaw.ac.at.
authors.forename: Juergen A
authors.initials: JA
authors.lastname: Knoblich
mesh_terms: D000818:Animals; D060049:Asymmetric Cell Division / Q000235:genetics*; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics* / Q000254:growth & development*; D007814:Larva / Q000235:genetics / Q000254:growth & development; D018613:Microscopy, Confocal; D058953:Neural Stem Cells / Q000166:cytology / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011679:Pupa / Q000235:genetics / Q000254:growth & development; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D025521:Tumor Suppressor Proteins; C070350:dlg1 protein, Drosophila