Abstract
Vertebrate hindbrain segmentation is a highly conserved process but the mechanism of rhombomere determination is not well understood. Recent work in the zebrafish has shown a requirement for fibroblast growth factor (Fgf) signaling and for the transcription factor variant hepatocyte nuclear factor 1 (vhnf1) in specification of rhombomeres 5 and 6 (r5+r6). We show here that vhnf1 functions in two ways to subdivide the zebrafish caudal hindbrain domain (r4-r7) into individual rhombomeres. First, vhnf1 promotes r5+r6 identity through an obligate synergy with Fgf signals to activate valentino and krox20 expression. Second, vhnf1 functions independently of Fgf signals to repress hoxb1a expression. Although vhnf1 is expressed in a broad posterior domain during gastrulation, it promotes the specification of individual rhombomeres. This is achieved in part because vhnf1 gives cellular competence to respond to Fgf signals in a caudal hindbrain-specific manner.
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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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Epistasis, Genetic
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Fibroblast Growth Factors / genetics
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Fibroblast Growth Factors / metabolism*
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Gene Expression Regulation, Developmental*
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Hepatocyte Nuclear Factor 1-beta
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Homeodomain Proteins / genetics
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Homeodomain Proteins / metabolism
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In Situ Hybridization
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MafB Transcription Factor
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Morphogenesis
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Nerve Tissue Proteins / genetics
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Nerve Tissue Proteins / metabolism
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism*
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Oligonucleotides, Antisense / genetics
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Oligonucleotides, Antisense / metabolism
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Rhombencephalon / anatomy & histology
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Rhombencephalon / embryology*
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Rhombencephalon / physiology
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Signal Transduction / physiology*
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Transcription Factors / genetics
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Transcription Factors / metabolism*
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Zebrafish / embryology*
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Zebrafish / genetics
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Zebrafish / metabolism
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Zebrafish Proteins*
Substances
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DNA-Binding Proteins
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HOXB1 homeodomain protein
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Hnf1b protein, rat
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Homeodomain Proteins
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MafB Transcription Factor
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Nerve Tissue Proteins
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Nuclear Proteins
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Oligonucleotides, Antisense
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Transcription Factors
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Zebrafish Proteins
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mafb protein, zebrafish
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Hepatocyte Nuclear Factor 1-beta
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Fibroblast Growth Factors