Molecular cloning and developmental expression of rat fibroblast growth factor receptor 3.

Fibroblast growth factors (FGFs) are involved in the control of a variety of biological functions including regulation and differentiation of various cell types. Furthermore, they play important roles in the processes of regeneration, angiogenesis, and chemotaxis. The family of FGF receptors (FGFRs) comprises four members, FGFR-1 to -4, which exist in several differentially expressed splice variants. Except for FGFR-3, primary structures and expression of the three other FGFRs have been described in the rat system. Although expression studies with heterologous probes of FGFR-3 from mice have been performed in the rat system, these analyses were limited and the complete set of receptors has not yet been revealed. To understand the developmental functions of FGFR-3, it is important to elucidate the expression pattern in embryos of different stages. In this study, we have isolated a cDNA of FGFR-3 from rat brain. Expression analyses by RT-PCR of adult rat revealed expression in several tissues, however, expression levels were highest in lung and brain. During embryonic development, FGFR-3 displays a diffuse expression in most tissues at embryonic day 14 (E14), as observed by in situ hybridization experiments. In E18 the expression pattern is more restricted, showing strong signals in spinal cord, dorsal root ganglia, cortex, chondrocytes, and endothelial cells. The temporal and spatial pattern of FGFR-3 expression suggests specific functions in several tissues during development.