PUBLICATION

Dynamic and sequential patterning of the zebrafish posterior hindbrain by retinoic acid

Authors
Maves, L., and Kimmel, C.B.
ID
ZDB-PUB-050818-15
Date
2005
Source
Developmental Biology   285(2): 593-605 (Journal)
Registered Authors
Kimmel, Charles B., Maves, Lisa
Keywords
Zebrafish, Hindbrain, Rhombomere, Segmentation, Retinoic acid, Retinaldehyde dehydrogenase, Hox, vHnf1, Valentino
MeSH Terms
  • Animals
  • Body Patterning/physiology*
  • Gene Expression Regulation, Developmental/drug effects
  • Gene Expression Regulation, Developmental/physiology*
  • In Situ Hybridization
  • Microspheres
  • Models, Biological*
  • Rhombencephalon/embryology*
  • Rhombencephalon/metabolism
  • Signal Transduction/drug effects
  • Signal Transduction/physiology*
  • Transcription Factors/metabolism
  • Tretinoin/metabolism*
  • Tretinoin/pharmacology
  • Zebrafish/embryology*
  • Zebrafish/metabolism
  • p-Aminoazobenzene/analogs & derivatives
  • p-Aminoazobenzene/pharmacology
PubMed
16102743 Full text @ Dev. Biol.
CTD
16102743
Abstract
A prominent region of the vertebrate hindbrain is subdivided along the anterior-posterior axis into a series of seven segments, or rhombomeres. The identity of each rhombomere is specified by the expression of conserved transcription factors, including Krox-20, vHnf1, Val (Kreisler, Mafb) and several Hox proteins. Previous work has shown that retinoic acid (RA) signaling plays a critical role in regulating the expression of these factors and that more posterior rhombomeres require higher levels of RA than more anterior rhombomeres. Models to account for RA concentration dependency have proposed either a static RA gradient or increasing time periods of RA exposure. Here, we provide evidence against both of these models. We show that early zebrafish rhombomere-specification genes, including vhnf1 in r5-r6 and hoxd4a in r7, initiate expression sequentially in the hindbrain, each adjacent to the source of RA synthesis in paraxial mesoderm. By knocking down RA signaling, we show that progressively more posterior rhombomeres require increasingly higher levels of RA signaling, and vhnf1 and hoxd4a expression are particularly RA-dependent. RA synthesis is required just at the time of initiation, but not for maintenance, of vhnf1 and hoxd4a expression. Furthermore, a premature RA increase causes premature activation of vhnf1 and hoxd4a expression. Our results support a new model of dynamic RA action in the hindbrain, in which a temporally increasing source of RA is required to sequentially initiate progressively more posterior rhombomere identities.
Genes / Markers
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Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Antibodies
Orthology
Engineered Foreign Genes
Mapping