FGF-8

FGF-8 is a developmental organizer rather than a routine mitogen. Multiple isoforms generated by alternative splicing and alternative translation initiation signal chiefly through FGFR1c, FGFR3c and FGFR4c. FGF-8 patterns the midbrain-hindbrain boundary from the isthmic organizer, directs limb-bud outgrowth, controls the migration of gonadotropin-releasing hormone neurons and participates in cardiac and pharyngeal development. In humans, FGF8 mutations cause hypogonadotropic hypogonadism with or without cleft lip and palate and have been linked to holoprosencephaly. Recombinant FGF-8b and other isoforms are standard tools for organoid patterning, dopaminergic neuron differentiation protocols and limb and neural development assays.