title: Bällchen participates in proliferation control and prevents the differentiation of Drosophila melanogaster neuronal stem cells.
abstract: Stem cells continuously generate differentiating daughter cells and are essential for tissue homeostasis and development. Their capacity to self-renew as undifferentiated and actively dividing cells is controlled by either external signals from a cellular environment, the stem cell niche, or asymmetric distribution of cell fate determinants during cell division. Here we report that the protein kinase Bällchen (BALL) is required to prevent differentiation as well as to maintain normal proliferation of neuronal stem cells of Drosophila melanogaster, called neuroblasts. Our results show that the brains of ball mutant larvae are severely reduced in size, which is caused by a reduced proliferation rate of the neuroblasts. Moreover, ball mutant neuroblasts gradually lose the expression of the neuroblast determinants Miranda and aPKC, suggesting their premature differentiation. Our results indicate that BALL represents a novel cell intrinsic factor with a dual function regulating the proliferative capacity and the differentiation status of neuronal stem cells during development.
authors.affiliation: Present address: Renal Division, University Hospital Freiburg, Hugstetter Strasse 55, 79106 Freiburg, Germany.
authors.forename: Toma
authors.initials: T
authors.lastname: Yakulov
authors.affiliation: Present address: Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK.
authors.forename: Ufuk
authors.initials: U
authors.lastname: Günesdogan
authors.affiliation: Max-Planck-Institut für biophysikalische Chemie, Abteilung Molekulare Entwicklungsbiologie, Am Fassberg 11, 37077 Göttingen, Germany Present address: Renal Division, University Hospital Freiburg, Hugstetter Strasse 55, 79106 Freiburg, Germany. Present address: Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK. Present address: Max-Planck-Institut für Infektionsbiologie, Department Cellular Microbiology, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: Herbert
authors.initials: H
authors.lastname: Jäckle
authors.affiliation: Present address: Max-Planck-Institut für Infektionsbiologie, Department Cellular Microbiology, Charitéplatz 1, 10117 Berlin, Germany. herzig@mpiib-berlin.mpg.de.
authors.forename: Alf
authors.initials: A
authors.lastname: Herzig
keywords: Bällchen; Drosophila; Neuroblasts; Stem cells