Identification of a dominant negative mutant of sprouty that potentiates fibroblast growth factor-but not epidermal growth factor-induced ERK activation
A. Sasaki et al., Identification of a dominant negative mutant of sprouty that potentiates fibroblast growth factor-but not epidermal growth factor-induced ERK activation, J BIOL CHEM, 276(39), 2001, pp. 36804-36808
Various mitogenic stimuli such as epidermal growth factor (EGF), fibroblast
growth factor (FGF), and phorbol 12,13-dibutyrate (PDBu) activate the Ras-
Raf-MEK-ERK pathway, but the regulatory mechanism of this pathway remains t
o be investigated. Here we found that in 293 cells, mammalian Sprouty2 and
Sprouty4 were rapidly induced by EGF, FGF, and PDBu in an ERK pathway-depen
dent manner. Forced expression of Sprouty2 and Sprouty4 inhibited FGF-induc
ed ERK activation but did not affect EGF- or PDBu-induced ERK activation. T
o examine whether endogenous Sproutys were also selective inhibitors, we ge
nerated a dominant negative form of Sprouty2 (Y55A) and Sprouty4 (Y53A) in
which conserved tyrosine residues were mutated. These mutants reverted the
suppressive effect of both Sprouty2 and Sprouty4 but not that of RasGAP or
SPRED (Sprouty-related EVH1 domain-containing protein), another Sprouty-rel
ated Ras suppressor. Expression of dominant negative Sprouty2 and Sprouty4
enhanced and prolonged FGF- but not EGF-induced ERK activation in 293 cells
. In PC12 cells, endogenous Sprouty4 was also induced by FGF. Overexpressio
n of wild-type Sprouty4 blocked FGF-induced differentiation, whereas Y53A-S
prouty4 enhanced it. These observations suggest that endogenous Sprouty2 an
d Sprouty4 are physiological negative feedback regulators of growth factor-
mediated ERK pathway and that there are Sprouty-sensitive and -insensitive
ERK activation pathways. Finding a dominant negative form of Sproutys will
facilitate the study of the molecular mechanism and physiological function
of Sproutys.