Differential TPA and PDGF-BB effects on subcellular localisation of PKC alpha and beta I in C3H/10T1/2 cells.
60-75% of PKC alpha and 30-40% of PKC beta I++ protein was located to the membranes and nuclear/nuclear associated endoplasmatic reticulum fractions of resting 10T1/2CI 8 mouse embryo fibroblasts. On average, 35% of the PKC alpha and 65% of the PKC beta I++ isoforms existed in a soluble state. Maximum PDGF-BB-mediated Erk1 activation was obtained without significant changes in soluble PKC alpha- or PKC beta I++- levels. The subcellular localisation of PKC alpha and PKC beta I was not affected by PDGF-BB treatment. 12-O-tetradecanoyl phorbol-13-acetate (TPA) caused translocation of cytoplasmic PKC alpha and beta I to the nucleus/nuclear associated endoplasmatic reticulum fraction. Down-regulation of PKC and bisindolylmaleimide I inhibited both TPA and PDGF-BB stimulated Erk1 activity. We are the first to show that PDGF-mediated activation of Erk1 involves a PKC-dependent step in 10T1/2CI 8 cells. We also provide novel evidence that PDGF-BB mediated Erk1 activation can take place in these cells without apparent recruitment of soluble PKC alpha/beta I to the particulate cell fractions.
Bjłrndal
B
B
Department of Molecular Biology, University of Bergen, Norway.
Helleland
C
C
Lillehaug
J R
JR
D000818:Animals; D000077214:Becaplermin; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D015151:Immunoblotting; D007527:Isoenzymes / Q000032:analysis*; D051379:Mice; D008809:Mice, Inbred C3H; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011493:Protein Kinase C / Q000032:analysis*; D020574:Proto-Oncogene Proteins c-sis; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D007527:Isoenzymes; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D000077214:Becaplermin; D011493:Protein Kinase C; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D013755:Tetradecanoylphorbol Acetate