Protein kinase C decreases the hepatocyte growth factor-induced activation of Erk1/Erk2 MAP kinases.

HGF and phorbol ester induce the scattering of HepG2 cells. Recently, we have reported that the motility and morphological responses that accompany this process require the activation of Erk1/Erk2 MAP kinases, and phosphatidylinositol 3-kinase contributes to the activation of Erk1/Erk2 in HGF-induced cells. The cell scattering-associated appearance of a high-M(r) (>300 kDa) protein pair has also been observed, and has been proven to be a sensitive marker of the intensity of Erk1/Erk2 activation. Our present study demonstrates that in HGF-induced cells protein kinase C and phosphatidylinositol 3-kinase regulate oppositely the expression of these cell scattering-associated proteins. While in phorbol ester-treated cells the sustained activation of protein kinase C is essential for this expression, in HGF-induced cells the inhibition of protein kinase C with bisindolylmaleimide I stimulates the expression. Protein kinase C reduces the HGF-induced phosphorylation of Erk1/Erk2, and in this way it can limit the intensity of Erk1/Erk2-dependent gene-expression