Distribution of FGF-5 in the rhesus macaque retina.

PURPOSE: To determine the distribution of mRNA transcribed from the FGF-5 gene and the distribution of FGF-5 protein in the normal adult retina of the rhesus macaque. METHODS: Freshly enucleated globes from rhesus macaque were prepared for Northern blot analysis, in situ hybridization, and immunohistochemical studies. A 350 base pair sequence from the human FGF-5 was subcloned and used to prepare 35S-labeled cRNAs for Northern and in situ experiments. Antipeptide antibodies were raised against an aminoterminal sequence as well as an internal sequence and were affinity purified on recombinant FGF-5 coupled to AffiGel-10. The specificity of antibody probes was verified by dot blot and Western blot analyses. RESULTS: Ganglion cells and photoreceptors express the highest levels of FGF-5 mRNA, although all neurons and the retinal pigment epithelium (RPE) were clearly labeled. Immunohistochemical staining similarly revealed a widespread distribution of the protein, with prominent labeling observed in photoreceptor inner segments, especially in cone cells. Plexiform layers and RPE cells were also clearly labeled. CONCLUSIONS: Clear evidence was established for the expression of FGF-5 in the retina, where it may play an important extracellular role as a secreted member of the FGF gene family.