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

Fibroblast growth factors (FGFs) are involved in the control of a variety o f biological functions including regulation and differentiation of various cell types. Furthermore, they play important roles in the processes of rege neration, angiogenesis, and chemotaxis. The family of FGF receptors (FGFRs) comprises four members, FGFR-1 to -4, which exist in several differentiall y expressed splice variants. Except for FGFR-3, primary structures and expr ession of the three other FGFRs have been described in the rat system. Alth ough expression studies with heterologous probes of FGFR-3 from mice have b een performed in the rat system, these analyses were limited and the comple te set of receptors has not yet been revealed. To understand the developmen tal functions of FGFR-3, it is important to elucidate the expression patter n 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 exp ression in most tissues at embryonic day 14 (E14), as observed by in situ h ybridization experiments. In E18 the expression pattern is more restricted, showing strong signals in spinal cord, dorsal root ganglia, cortex, chondr ocytes, and endothelial cells. The temporal and spatial pattern of FGFR-3 e xpression suggests specific functions in several tissues during development .