Comparison of the intracellular signaling responses by three chimeric fibroblast growth factor receptors in PC12 cells

Stably transfected PC12 cell lines expressing similar amounts of chimeric r eceptors composed of the extracellular domain of the human platelet-derived growth factor (PDGF)beta receptor and the transmembrane and intracellular domains of the fibroblast growth factor receptors (FCFRs) 1, 3, and 1 under go ligand-induced differentiation. The FGFR1 chimera (PFR1) is the most pot ent of the three, and PFR4 requires more frequent (every 24 hr) addition of ligand to maintain the response. Both PFR1 and -3 also show significant li gand-independent autophosphorylation but PFR4 does not. hll of the chimeras activated phospholipase Cy, Shc, FGFR substrate (FRS)2, and the mitogen-ac tivated protein kinases, ERK1 and 2. PFR4 was moderately weaker in stimulat ing these effects as Kell; PFR1 and -3 were comparable, None of the chimera s induced Sos association or were coprecipitated with Shc. Cotransfection o f a dominant-negative Shc derivative, with tyrosine at 239, 240, and 317 re placed with phenylalanine, in the PFR-expressing cells was without effect o n PDGF-induced neurite outgrowth. The same derivative substantially inhibit ed the response of these cells to SGF, These results indicate that FGFR1, 3 , and i (i) are capable of signaling in a similar fashion; (ii) primarily u se FRS2 and, perhaps, PLC gamma; and (iii) do not utilize Shc. The results also suggest that the principal difference between FGFR1, 3, and i is in th e strength of the tyrosine kinase activity and that qualitative differences in signaling capacity are likely to be less important.