title: seven-up Controls switching of transcription factors that specify temporal identities of Drosophila neuroblasts.
abstract: Drosophila neuronal stem cell neuroblasts (NB) constantly change character upon division, to produce a different type of progeny at the next division. Transcription factors Hunchback (HB), Krüppel (KR), Pdm (PDM), etc. are expressed sequentially in each NB and act as determinants of birth-order identity. How a NB switches its expression profile from one transcription factor to the next is poorly understood. We show that the HB-to-KR switch is directed by the nuclear receptor Seven-up (SVP). SVP expression is confined to a temporally restricted subsection within the NB's lineage. Loss of SVP function causes an increase in the number of HB-positive cells within several NB lineages, whereas misexpression of svp leads to the loss of these early-born neurons. Lineage analysis provides evidence that svp is required to switch off HB at the proper time. Thus, svp modifies the self-renewal stem cell program to allow chronological change of cell fates, thereby generating neuronal diversity.
authors.affiliation: Division of Developmental Genetics, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan.
authors.forename: Makoto I
authors.initials: MI
authors.lastname: Kanai
authors.forename: Masataka
authors.initials: M
authors.lastname: Okabe
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Hiromi
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D002454:Cell Differentiation; D002455:Cell Division; D002490:Central Nervous System / Q000166:cytology / Q000196:embryology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004330:Drosophila / Q000166:cytology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D051741:Kruppel-Like Transcription Factors; D039902:Multipotent Stem Cells / Q000166:cytology; D009154:Mutation; D009474:Neurons / Q000166:cytology*; D011987:Receptors, Steroid / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C497244:Kr protein, Drosophila; D051741:Kruppel-Like Transcription Factors; D011987:Receptors, Steroid; D012097:Repressor Proteins; D014157:Transcription Factors; C061245:hb protein, Drosophila; C094295:svp protein, Drosophila