Recombinant Mouse FGF-8c Protein, CF

FGF-8 is a member of the fibroblast growth factor family that was originally discovered as a growth factor essential for the androgen-dependent growth of mouse mammary carcinoma cells (1 - 3). Alternate splicing of mouse FGF-8 mRNA generates eight secreted isoforms, designated a - h, but only FGF-8a, b, e and f exist in humans (4). FGF-8 contains a 22 amino acid (aa) signal sequence, an N-terminal domain that varies according to the isoform (84 aa for FGF-8c; 20 aa for the shortest, FGF-8a), a 125 aa FGF domain and a 37 aa proline-rich C-terminal sequence. The FGF domain of FGF-8 shares the most aa identity with FGF17 (75%) and FGF-18 (67%), and the three form an FGF subfamily (2). Unique portions of FGF-8c are reported only for mouse, but the mouse FGF-8a sequence, which is common to all isoforms, shares 100% aa identity with human, rat and bovine FGF-8a, and 99%, 83%, 83% and 78% aa identity with canine, Xenopus, chicken and zebrafish FGF-8a, respectively. FGF-8 is widely expressed during embryogenesis, and mediates epithelial-mesenchymal transitions. It plays an organizing and inducing role during gastrulation, and regulates patterning of the midbrain/hindbrain, eye, ear, limbs and heart in the embryo (2, 5 - 8). The isoforms may play different roles in development. FGF-8b shows the strongest receptor affinity and oncogenic transforming capacity; while FGF-8c shows little transforming capacity (1, 5, 9 - 12). FGF-8 shows limited expression in the normal adult, but low levels are found in the reproductive and genitourinary tract, peripheral leukocytes and bone marrow hematopoietic cells (3, 9, 13).