Expression of the FGF receptor 2 gene (fgfr2) during embryogenesis in the zebrafish Danio rerio

Abstract

We isolated a full-length cDNA clone for the zebrafish homologue of fibroblast growth factor receptor (FGFR) 2. The deduced protein sequence is typical of vertebrate FGFRs in that it has three Ig-like domains in the extracellular region. The expression of fgfr2 is initiated during epiboly in the paraxial mesoderm. During early somitogenesis, fgfr2 expression was noted in the anterior neural plate as well as in newly formed somites. Whereas fgfr2 expression in somites is transient, it increases in the central nervous system (CNS), i.e. in the ventral telencephalon, anterior diencephalon, midbrain, and respective rhombomeres of the hindbrain, from the mid-somitogenesis stage. The dorsal telencephalon and the region around the midbrain-hindbrain boundary are devoid of fgfr2 expression. Essentially the same expression pattern is observed until 48 h post-fertilization in the CNS, although rhombomeric expression in the hindbrain is progressively confined to narrower stripes. After somitogenesis, fgfr2 expression was also observed in the lens, hypochord, endoderm, and fin mesenchyme. We compared the expression of the four fgfr genes (fgfr1-4) in the CNS of zebrafish embryos and show that fgfr1 is the only fgfr gene that is expressed in the dorsal telencephalon and isthmic region from which expression of fgfr2-4 is absent.

Fgf receptors Fgfr1a and Fgfr2 control the function of pharyngeal endoderm in late cranial cartilage development

“…We further show that fgfr1a and fgfr2 expression largely overlaps in pharyngeal endoderm at 48 hpf. This is consistent with the previously described expression for fgfr1a in the pharyngeal arches (Ota et al, 2010) and fgfr2 in axial mesoderm and endoderm at 24 hpf (Tonou-Fujimori et al, 2002). In our experiments, fgfr2 mRNA was weakly detected in the pharyngeal region at 24 hpf, but clearly observed at 26 hpf, suggesting that its endodermal expression starts around this stage.…”

“…As the dominant negative receptor blocks signaling by interacting with endogenous receptors in the cells where it is expressed, we decided to study the role of Fgfr1a and Fgfr2 receptors by antisense morpholino injection, as both were previously shown to be expressed in the pharyngeal region at 24 hpf (Tonou-Fujimori et al, 2002;Ota et al, 2010). Depletion of each Fgfr1a or Fgfr2 leads to severe defects in cranial cartilage formation, similar to those observed upon Fgf inhibition after 24 hpf.…”

Fgf8 drives myogenic progression of a novel lateral fast muscle fibre population in zebrafish

“…kinase Fgf receptors, several of which are expressed in zebrafish somites, although their role there is unknown (Klint and Claesson-Welsh, 1999;Thisse et al, 1995;Tonou-Fujimori et al, 2002). In fish, a mutation in fgf8 has been reported to diminish myod expression (Reifers et al, 1998).…”

Endoderm-derived Fgf3 is necessary and sufficient for inducing neurogenesis in the epibranchial placodes in zebrafish

“…Our recent literature and database searches have revealed at least 25 candidate Fgf members in zebrafish (http://www.sanger.ac.uk/Projects/D_rerio). The effects of vertebrate Fgfs are mediated by four transmembrane receptors (Fgfr1 through Fgfr4), which are members of the receptor tyrosine kinase (RTK) superfamily (Ornitz, 2000;Scholpp et al, 2004;Sleptsova-Friedrich et al, 2001;Thisse et al, 1995;Tonou-Fujimori et al, 2002). Upon ligand binding, Fgfrs trigger, by way of Ras, a sequential activation of the mitogen-activated kinase (MAPK)/extracellular activated kinase (ERK) signaling cascade (Cobb and Goldsmith, 1995), which in turn leads to the activation of nuclear transcription.…”