Transcriptional activation of c-fos by oncogenic Ha-Ras in mouse mammary epithelial cells requires the combined activities of PKC-lambda, epsilon and zeta.
The implication of protein kinase C (PKC) isoforms cPKC-alpha, nPKC-epsilon, aPKC-lambda and aPKC-zeta in the transcriptional activation of a c-fos promoter-driven CAT-reporter construct by transforming Ha-Ras has been investigated. This was achieved by employing antisense constructs encoding RNA directed against isoform-specific 5' sequences of the corresponding mRNA, and expression of PKC mutants representing either kinase-defective, dominant negative, or constitutively active forms of the PKC isoforms. The data indicate that in HC11 mouse mammary epithelial cells, transforming Ha-Ras requires the activities of the three PKC isozymes: aPKC-lambda, nPKC-epsilon and aPKC-zeta, not, however, of cPKC-alpha, for the transcriptional activation of c-fos. Co-expression of oncogenic Ha-Ras with combinations of kinase-defective, dominant negative and constitutively active mutants of the various PKC isozymes are in agreement with a tentative model suggesting that, in the signaling pathway from Ha-Ras to the c-fos promoter, aPKC-lambda acts upstream whereas aPKC-zeta functions downstream of nPKC-epsilon.
Institute of Medical Chemistry and Biochemistry and the Institute of Medical Biology, University of Innsbruck, A-6020, Innsbruck, Austria.
S
S
Kampfer
K
K
Hellbert
A
A
Villunger
W
W
Doppler
G
G
Baier
H H
HH
Grunicke
F
F
Uberall
D000818:Animals; D002460:Cell Line; D004847:Epithelial Cells / Q000378:metabolism*; D016762:Genes, fos / Q000235:genetics*; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D048369:MAP Kinase Kinase 1; D008321:Mammary Glands, Animal / Q000166:cytology; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases; D015689:Oncogene Protein p21(ras) / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D011505:Protein-Tyrosine Kinases / Q000502:physiology; D019908:Proto-Oncogene Proteins c-raf / Q000502:physiology; D016372:RNA, Antisense; D015398:Signal Transduction / Q000235:genetics; D015533:Transcriptional Activation / Q000502:physiology*; D014162:Transfection
D007527:Isoenzymes; D016372:RNA, Antisense; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D011493:Protein Kinase C; D048369:MAP Kinase Kinase 1; C482127:Map2k1 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases; D015689:Oncogene Protein p21(ras)