Protein kinase C mu selectively activates the mitogen-activated protein kinase (MAPK) p42 pathway

Here we show that human protein kinase C mu (PKC mu) activates the mitogen- activated protein kinase (MAPK). Transient expression of constitutive activ e PKC mu leads to an activation of Raf-1 kinase as demonstrated by in vitro phosphorylation of MAPK, PKC mu enhances transcriptional activity of a bas al thymidine kinase promotor containing serum response elements (SREs) as s hown by luciferase reporter gene assays. SRE driven gene activation by PKC mu is triggered by the Elk-1 ternary complex factor. PKC mu -mediated activ ation of SRE driven transcription can be inhibited by the MEK1 inhibitor PD 98059, In contrast to the activation of the p42/ERK1 MAPK cascade, transien t expression of constitutive active PKC mu does neither affect c-jun N-term inal kinase nor p38 MAPK. (C) 2001 Federation of European Biochemical Socie ties, Published by Elsevier Science B.V. All rights reserved.