Genomic organization and embryonic expression of the mouse fibroblast growth factor 9 gene

Fibroblast growth factor 9 (FGF9), originally cloned as glial-activating factor from human glioma cells, is expressed in adult rat brain and kidney. Here we report the chromosomal localization, genomic organization, and embryonic expression pattern of the mouse Fgf9 gene. Fgf9 maps to chromosome 14 near the Ctla6 locus. The gene spans more than 34 kb and contains three exons and two introns. Translation initiation occurs in exon 1, and translation termination occurs in exon 3. Fgf9 RNA was detected during mouse embryogenesis in several tissues in which Fgf gene expression has not been previously described, including intermediate mesoderm of late-stage gastrulation, ventricular myocardium, lung pleura, skeletal myoblasts in the early limb bud, spinal cord motor neurons, olfactory bulb, and gut lumenal epithelium. Fgf9 is coexpressed with other Fgf genes in some skeletal myoblasts, in limb apical ectoderm, in craniofacial ectoderm, and in the retina, inner ear, and tooth bud.