Abstract
Here we present the identification and characterization of dHb9, the Drosophila homolog of vertebrate Hb9, which encodes a factor central to motorneuron (MN) development. We show that dHb9 regulates neuronal fate by restricting expression of Lim3 and Even-skipped (Eve), two homeodomain (HD) proteins required for development of distinct neuronal classes. Also, dHb9 and Lim3 are activated independently of each other in a virtually identical population of ventrally and laterally projecting MNs. Surprisingly, dHb9 represses Lim3 cell nonautonomously in a subset of dorsally projecting MNs, revealing a novel role for intercellular signaling in the establishment of neuronal fate in Drosophila. Lastly, we provide evidence that dHb9 and Eve regulate each other's expression through Groucho-dependent crossrepression. This mutually antagonistic relationship bears similarity to the crossrepressive relationships between pairs of HD proteins that pattern the vertebrate neural tube.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Bacterial Proteins*
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Basic Helix-Loop-Helix Transcription Factors
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Cell Communication / genetics
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Cell Differentiation / genetics
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Cell Lineage / genetics*
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Chemotaxis / genetics
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Choristoma / genetics
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Choristoma / metabolism
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism
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Drosophila Proteins / genetics
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Drosophila Proteins / metabolism
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Drosophila melanogaster / cytology
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Drosophila melanogaster / embryology*
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Drosophila melanogaster / genetics
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Embryo, Nonmammalian / cytology
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Embryo, Nonmammalian / embryology*
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Embryo, Nonmammalian / metabolism
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Female
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Gene Expression Regulation, Developmental / genetics*
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Growth Cones / metabolism
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Growth Cones / ultrastructure
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Homeodomain Proteins / genetics
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Homeodomain Proteins / metabolism*
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Male
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Molecular Sequence Data
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Motor Neurons / cytology
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Motor Neurons / metabolism*
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Mutation / genetics
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Nerve Tissue Proteins / genetics
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Nerve Tissue Proteins / metabolism
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Nervous System / cytology
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Nervous System / embryology*
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Nervous System / metabolism
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Repressor Proteins / genetics
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Repressor Proteins / metabolism
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Sequence Homology, Amino Acid
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Transcription Factors / genetics
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Transcription Factors / metabolism*
Substances
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Bacterial Proteins
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Basic Helix-Loop-Helix Transcription Factors
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DNA-Binding Proteins
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Drosophila Proteins
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Homeodomain Proteins
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Nerve Tissue Proteins
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Repressor Proteins
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Transcription Factors
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eve protein, Drosophila
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exex protein, Drosophila
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gro protein, Drosophila