Comprehensive analysis of fibroblast growth factor receptor expression patterns during chick forelimb development

Abstract

Specific interactions between fibroblast growth factors (Fgf1-22) and their tyrosine kinase receptors (FgfR1-4) activate different signalling pathways that are responsible for the biological processes in which Fgf signalling is implicated during embryonic development. In the chick, several Fgf ligands (Fgf2, 4, 8, 9, 10, 12, 13 and 18 ) and the four FgfRs (FgfR 1, 2, 3 and 4) have been reported to be expressed in the developing limb. The precise spatial and temporal expression of these transcripts is important to guide the limb bud to develop into a wing/leg. In this paper, we present a detailed and systematic analysis of the expression patterns of FgfR1, 2, 3 and 4 throughout chick wing development, by in situ hybridisation on whole mounts and sections. Moreover, we characterize for the first time the different isoforms of FGFR1-3 by analysing their differential expression in limb ectoderm and mesodermal tissues, using RT-PCR and in situ hybridisation on sections. Finally, isoform-specific sequences for FgfR1IIIb, FgfR1IIIc, FgfR3IIIb and FgfR3IIIc were determined and deposited in GenBank with the following accession numbers: GU053725, GU065444, GU053726, GU065445, respectively. KEY WORDS: Fgf, FgfRs, limb, chickThe developing chick limb grows out as a protrusion of mesenchymal cells from the lateral plate mesoderm and adjacent somites. Cells from the lateral plate mesoderm form cartilage and connective tissues, such as muscle sheaths, tendons and ligaments. Meanwhile, myogenic precursor cells delaminate from the lateral part of the somites, migrate to the limb bud, colonise the dorsal and ventral limb regions and activate the myogenic program to differentiate into multinucleated myotubes, thus generating the definitive limb skeletal muscles (Christ and Brand-Saberi, 2002;Duprez, 2002;Buckingham et al. 2003). The mesenchyme of the limb bud is enveloped by an ectodermal jacket, whose distal tip forms a specialised epithelial structure, the apical ectodermal ridge (AER) (Todt and Fallon, 1984). Mesenchymal cells directly under the AER remain undifferentiated and populate the so-called undifferentiated zone (Tabin and Wolpert, 2007). Condensation of the cartilage elements proceeds in a proximal to distal direction based on cells' temporal and positional values, which could be provided by the reported limb molecular clock (Pascoal et al. 2007a; reviewed in Pascoal and Palmeirim, 2007;Tabin and Wolpert, 2007).Int. J. Dev. Biol. 54: 1517-1526 (2010) doi: 10.1387/ijdb.092887cs Abbreviations used in this paper: AER, apical ectodermal ridge; Fgf, fibroblast growth factor; FgfR, Fgf receptor; ZPA, zone of polarizing activity.During development, changes occur along the three limb bud axes -anterior-posterior (AP), dorsal-ventral (DV) and proximaldistal (PD) -conducted by three distinct signalling centres, the zone of polarizing activity (ZPA), the dorsal (non-ridge) ectoderm and the AER, respectively (reviewed in Towers and Tickle, 2009). ZPA activity is mediated by the diffusible molecule Sonic hedgehog (Shh...

Detection of isoform‐specific fibroblast growth factor receptors by whole‐mount in situ hybridization in early chick embryos

“…For example, in HH stage 24 chick wing buds, as assessed with RT-PCR, FGFR2b is expressed only in the ectoderm, whereas FGFR2c and FGFR3c are expressed only in the mesenchyme. In contrast, FGFR1b , FGFR1c , and FGFR3c are expressed in both ectoderm and mesenchyme (Sheeba et al, 2010). Moreover, in the developing chick mandible (HH stages 22–30), as assessed with section in situ hybridization, FGFR2b is expressed mainly in the epithelium, whereas FGFR2c is expressed in the mesenchyme, including Meckel’s cartilage (Havens et al, 2006).…”

Fibroblast growth factor signaling in skeletal development and disease

“…1A) Fgfr2 expression is increased (compared with the surrounding mesenchyme) and initially overlaps with domains of Sox9 expression (Orr-Urtreger et al 1991;Peters et al 1992;Szebenyi et al 1995;Delezoide et al 1998;Eswarakumar et al 2002;Sheeba et al 2010). Fgfr1 is more uniformly expressed throughout limb bud mesenchyme.…”

“…Fgfr1 is more uniformly expressed throughout limb bud mesenchyme. Although Fgfr3 and Fgfr4 are excluded from distal limb bud mesenchyme, these Fgfrs are expressed in more proximal locations in tissues corresponding to developing muscle (OrrUrtreger et al 1991;Peters et al 1992;Szebenyi et al 1995;Delezoide et al 1998;Sheeba et al 2010). Cells in the periphery of the condensation that will form perichondrium and periosteum express both Fgfr1 and Fgfr2 ( Fig.…”

“…1). At precondensation stages, distal limb bud mesenchyme expresses both Fgfr1 and Fgfr2 (Orr-Urtreger et al 1991;Sheeba et al 2010), whereas Fgfr3 and Fgfr4 are not detected in undifferentiated distal limb bud mesenchyme (Sheeba et al 2010). Distal limb bud FGFRs respond to FGFs produced by the apical ectodermal ridge (AER) of the limb bud (Zeller et al 2009).…”

Signaling pathways influencing tumor microenvironment and their exploitation for targeted drug delivery

“…There are 4 FGFRs (FGFR1-4) and 22 FGF ligands [15]. Binding of FGF ligands to FGFRs activate several downstream signaling pathways, including Ras/ MAPK/ERK, PLCγ/PKC, PI3K/Akt, and JAK/STAT.…”