title: Genome-wide identification of Drosophila Hb9 targets reveals a pivotal role in directing the transcriptome within eight neuronal lineages, including activation of nitric oxide synthase and Fd59a/Fox-D.
abstract: Hb9 is a homeodomain-containing transcription factor that acts in combination with Nkx6, Lim3, and Tail-up (Islet) to guide the stereotyped differentiation, connectivity, and function of a subset of neurons in Drosophila. The role of Hb9 in directing neuronal differentiation is well documented, but the lineage of Hb9(+) neurons is only partly characterized, its regulation is poorly understood, and most of the downstream genes through which it acts remain at large. Here, we complete the lineage tracing of all embryonic Hb9(+) neurons (to eight neuronal lineages) and provide evidence that hb9, lim3, and tail-up are coordinately regulated by a common set of upstream factors. Through the parallel use of micro-array gene expression profiling and the Dam-ID method, we searched for Hb9-regulated genes, uncovering transcription factors as the most over-represented class of genes regulated by Hb9 (and Nkx6) in the CNS. By a nearly ten-to-one ratio, Hb9 represses rather than activates transcription factors, highlighting transcriptional repression of other transcription factors as a core mechanism by which Hb9 governs neuronal determination. From the small set of genes activated by Hb9, we characterized the expression and function of two - fd59a/foxd, which encodes a transcription factor, and Nitric oxide synthase. Under standard lab conditions, both genes are dispensable for Drosophila development, but Nos appears to inhibit hyper-active behavior and fd59a appears to act in octopaminergic neurons to control egg-laying behavior. Together our data clarify the mechanisms through which Hb9 governs neuronal specification and differentiation and provide an initial characterization of the expression and function of Nos and fd59a in the Drosophila CNS.
authors: Department of Genetics, Washington University School of Medicine, St. Louis 4566, Scott Avenue, St. Louis, MO 63110, USA.
authors: Haluk
authors: H
authors: Lacin
authors: Department of Genetics, Washington University School of Medicine, St. Louis 4566, Scott Avenue, St. Louis, MO 63110, USA.
authors: Jannette
authors: J
authors: Rusch
authors: Department of Genetics, Washington University School of Medicine, St. Louis 4566, Scott Avenue, St. Louis, MO 63110, USA.
authors: Raymond T
authors: RT
authors: Yeh
authors: Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA.
authors: Miki
authors: M
authors: Fujioka
authors: Department of Genetics, Washington University School of Medicine, St. Louis 4566, Scott Avenue, St. Louis, MO 63110, USA.
authors: Beth A
authors: BA
authors: Wilson
authors: Department of Genetics, Washington University School of Medicine, St. Louis 4566, Scott Avenue, St. Louis, MO 63110, USA.
authors: Yi
authors: Y
authors: Zhu
authors: Howard Hughes Medical Institute, Janelia Farm Research Campus (HHMI JFRC), Ashburn, VA, USA.
authors: Alice A
authors: AA
authors: Robie
authors: Department of Genetics, Washington University School of Medicine, St. Louis 4566, Scott Avenue, St. Louis, MO 63110, USA.
authors: Hemlata
authors: H
authors: Mistry
authors: Department of Genetics, Washington University School of Medicine, St. Louis 4566, Scott Avenue, St. Louis, MO 63110, USA.
authors: Ting
authors: T
authors: Wang
authors: Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA.
authors: James B
authors: JB
authors: Jaynes
authors: Department of Genetics, Washington University School of Medicine, St. Louis 4566, Scott Avenue, St. Louis, MO 63110, USA. Electronic address: jskeath@genetics.wustl.edu.
authors: James B
authors: JB
authors: Skeath
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D002454:Cell Differentiation; D019070:Cell Lineage; D002490:Central Nervous System / Q000196:embryology; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics* / Q000502:physiology*; D004742:Enhancer Elements, Genetic; D051858:Forkhead Transcription Factors / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D056726:Genetic Association Studies; D005838:Genotype; D018398:Homeodomain Proteins / Q000378:metabolism*; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009474:Neurons / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D011401:Promoter Regions, Genetic; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000378:metabolism*; D059467:Transcriptome
chemical_list: D029721:Drosophila Proteins; D051858:Forkhead Transcription Factors; D018398:Homeodomain Proteins; D014157:Transcription Factors; C490005:exex protein, Drosophila; C588216:fd59a protein, Drosophila; D019001:Nitric Oxide Synthase
keywords: Drosophila; FoxD/fd59a; Hb9; Neurogenesis; Nitric oxide synthase