Structural basis by which alternative splicing modulates the organizer activity of FGF8 in the brain

• DOI: 10.1101/gad.1365406
• Publication Date: 2005-12-30T01:38:35Z
• Authors: Shaun K. Olsen; James Y.H. Li; Carrie Bromleigh; Anna V. Eliseenkova; Omar A. Ibrahimi; Zhimin Lao; Fuming Zhang; Robert J. Linhardt; Alexandra L. Joyner; Moosa Mohammadi
• Keywords: FGF8; Hindbrain

Two of the four human FGF8 splice isoforms, FGF8a and FGF8b, are expressed in mid-hindbrain region during development. Although only difference between these isoforms is presence an additional 11 amino acids at N terminus possess remarkably different abilities to pattern midbrain anterior hindbrain. To reveal structural basis by which alternative splicing modulates organizing activity FGF8, we solved crystal structure FGF8b complex with "c" isoform FGF receptor 2 (FGFR2c). Using surface plasmon resonance (SPR), also characterized receptor-binding specificity "b" FGF17 (FGF17b), FGF18. The FGF8b-FGFR2c shows that permits a single contact phenylalanine 32 (F32) hydrophobic groove within Ig domain 3 present FGFR1c, FGFR3c, FGFR4. Consistent structure, mutation F32 alanine reduces affinity toward all receptors levels characteristic FGF8a. More importantly, analysis patterning ability FGF8b(F32A) mutant chick embryos murine explants this functionally converts Moreover, our data suggest intermediate affinities FGF17b FGF18, relative account for distinct two ligands. We show mode from other FGFs provide first biochemical evidence physiological FGF8b-FGFR1c interaction indispensable role embryonic development, binding appeared as early nematodes has been preserved throughout evolution.