Lc. Warner et al., RAS IS REQUIRED FOR EPIDERMAL GROWTH FACTOR-STIMULATED ARACHIDONIC-ACID RELEASE IN RAT-1 FIBROBLASTS, Oncogene, 8(12), 1993, pp. 3249-3255
Previous studies have provided suggestive evidence for an interaction
between ras activation and signalling pathways involved in agonist-sti
mulated arachidonic acid release in a variety of cell systems. In orde
r to clarify this interaction, we have measured epidermal growth facto
r (EGF)-stimulated arachidonic acid release in rat-1 fibroblasts trans
fected with the N-17 dominant negative mutation of ras. Cells transfec
ted with the N-17 ras mutant, display a markedly attenuated arachidoni
c acid-release response to EGF, compared to sham-transfected and non-t
ransfected cells. In contrast, the response to phorbol myristate aceta
te (PMA) was not attenuated in the N-17-mutant expressing cells. No di
fferences were detected between sham-transfected and N-17 mutant expre
ssing cells in levels of immunodetectable EGF receptor, cytosolic phos
pholipase A(2) or mitogen-activated protein (MAP) kinase. Attenuation
of EGF-stimulated arachidonic acid release in the N-17 mutant expressi
ng cells, was accompanied by a marked diminution in EGF-stimulated tyr
osine phosphorylation of MAP kinase. We conclude that the signalling p
athway involved in epidermal growth factor-stimulated arachidonic acid
release is similar to the signalling pathway for mitogenic responses
to epidermal growth factor and requires ras activation, likely followe
d by a downstream cascade of kinases eventuating in MAP kinase activat
ion.