ZFIN ID: ZDB-PUB-130418-10
Zebrafish Foxi1 provides a neuronal ground state during inner ear induction preceding the Dlx3b/4b-regulated sensory lineage
Hans, S., Irmscher, A., and Brand, M.
Date: 2013
Source: Development (Cambridge, England)   140(9): 1936-1945 (Journal)
Registered Authors: Brand, Michael, Hans, Stefan
Keywords: inner ear, neurogenesis, competence, Foxi1, Dlx3b/4b, genetic lineage tracing, Cre/lox, PioTrack, zebrafish
MeSH Terms:
  • Animals
  • Animals, Genetically Modified/embryology
  • Animals, Genetically Modified/genetics
  • Animals, Genetically Modified/metabolism
  • Cell Lineage
  • Ear, Inner/embryology*
  • Ear, Inner/physiology
  • Embryo, Nonmammalian/drug effects
  • Embryo, Nonmammalian/metabolism
  • Embryo, Nonmammalian/physiology
  • Forkhead Transcription Factors/genetics
  • Forkhead Transcription Factors/metabolism*
  • Gene Expression Regulation, Developmental
  • Genes, Reporter
  • Hair Cells, Auditory/metabolism*
  • Homeodomain Proteins/genetics
  • Homeodomain Proteins/metabolism*
  • Immunohistochemistry
  • Morpholinos/administration & dosage
  • Neurogenesis
  • Neurons/metabolism
  • Neurons/physiology
  • PAX2 Transcription Factor/genetics
  • PAX2 Transcription Factor/metabolism
  • Promoter Regions, Genetic
  • SOX9 Transcription Factor/genetics
  • SOX9 Transcription Factor/metabolism
  • Transcription, Genetic
  • Zebrafish/embryology
  • Zebrafish/metabolism*
  • Zebrafish/physiology
  • Zebrafish Proteins/genetics
  • Zebrafish Proteins/metabolism*
PubMed: 23571216 Full text @ Development

Vertebrate inner ear development is a complex process that involves the induction of a common territory for otic and epibranchial precursors and their subsequent segregation into otic and epibranchial cell fates. In zebrafish, the otic-epibranchial progenitor domain (OEPD) is induced by Fgf signaling in a Foxi1- and Dlx3b/4b-dependent manner, but the functional differences of Foxi1 and Dlx3b/4b in subsequent cell fate specifications within the developing inner ear are poorly understood. Based on pioneer tracking (PioTrack), a novel Cre-dependent genetic lineage tracing method, and genetic data, we show that the competence to embark on a neuronal or sensory fate is provided sequentially and very early during otic placode induction. Loss of Foxi1 prevents neuronal precursor formation without affecting hair cell specification, whereas loss of Dlx3b/4b inhibits hair cell but not neuronal precursor formation. Consistently, in Dlx3b/4b- and Sox9a-deficient b380 mutants almost all otic epithelial fates are absent, including sensory hair cells, and the remaining otic cells adopt a neuronal fate. Furthermore, the progenitors of the anterior lateral line ganglia also arise from the OEPD in a Foxi1-dependent manner but are unaffected in the absence of Dlx3b/4b or in b380 mutants. Thus, in addition to otic fate Foxi1 provides neuronal competence during OEPD induction prior to and independently of the Dlx3b/4b-mediated sensory fate of the developing inner ear.