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Microbead Implantation in the Zebrafish Embryo
Published on: July 30, 2015
FGF signaling regulates otic placode induction and refinement by controlling both ectodermal target genes and
Lisa D Urness1, Christian N Paxton, Xiaofen Wang
1Department of Human Genetics, University of Utah, 15 N 2030 E, RM 2100, Salt Lake City, UT 84112-5330, USA.
Developmental Biology
|February 23, 2010
Summary
Fibroblast Growth Factor (FGF) signaling is crucial for inner ear development. FGF3 and FGF10 deficiency disrupts gene expression, impacting otic placode formation and Wnt8a signaling, essential for hearing and balance development.
Area of Science:
- Developmental Biology
- Genetics
- Otolaryngology
Background:
- The inner ear, responsible for hearing and balance, develops from the otic placode, a specialized region of head ectoderm.
- Fibroblast Growth Factors (FGFs), specifically FGF3 and FGF10, are critical for initiating inner ear development by regulating gene expression in the pre-otic field.
Purpose of the Study:
- To identify the transcriptional blueprint regulating inner ear development.
- To understand the role of FGF3 and FGF10 in otic placode gene expression and induction.
Main Methods:
- Microarray analysis to compare gene expression in control and FGF3/FGF10 deficient mouse embryos.
- In situ hybridization to validate differential gene expression.
- Assays of candidate target genes and Wnt signaling pathways.
- Chick explant assays to test FGF-induced Wnt8a expression.
Main Results:
- FGF3 and FGF10 deficiency led to down-regulation of key genes like Hmx3, Hmx2, Foxg1, Sox9, Has2, and Slc26a9.
- Placode markers Fgf4 and Foxi3 were down-regulated, while the cranial epidermis marker Foxi2 was expanded in double mutants.
- Wnt8a expression was reduced or absent in FGF-deficient embryos, indicating FGF's role in Wnt8a regulation.
- FGF3 and FGF4, but not FGF10, could induce Wnt8a expression in chick explants.
Conclusions:
- FGF signaling, particularly FGF3, is essential for specifying the pre-otic field and subsequently inducing Wnt8a expression.
- Wnt8a acts as a crucial link between FGF signaling and the restriction of the otic placode to the hindbrain-adjacent ectoderm.
- This study elucidates a key FGF-Wnt signaling axis in the transcriptional control of early inner ear development.
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