Protein kinase C-independent activation of mitogen-activated protein kinase by epidermal growth factor in skin fibroblasts.
In this study, we demonstrated that epidermal growth factor (EGF) stimulated the phosphorylation of myelin basic protein (MBP), a mitogen-activated protein kinase (MAPK) substrate, in crude extracts of human dermal fibroblasts. Moreover, using a selective protein kinase C inhibitor, GF 109203X (3-[1-[3-(dimethylamino)propyl]-1 H-indol-3-yl]-4 (1 H-indol-3-yl)-1 H-pyrrole-2,5-dione monohydrochloride), we observed that protein kinase C was partially involved in the total MBP phosphorylation. To determine the role of protein kinase C in the MBP phosphorylation, we separated, using fast protein liquid chromatography, the proteins present in the fibroblast crude extracts; we thus detected two distinct MBP kinase activities. The first one was stimulated by EGF and corresponded to p42mapk and p44mapk isoforms; this stimulation was not modified by GF 109203X. The second MBP kinase activity was not stimulated by EGF and was due to two protein kinase C isoforms reacting with an anti-protein kinase C zeta antibody. These results show that, in human dermal fibroblasts, EGF stimulates p42mapk and p44mapk isoforms in a protein kinase C-independent manner.
Le Panse
R
R
INSERM Unité 312, Laboratoire de Dermatologie (Pr. Dubertret), Hôpital Saint Louis, Paris, France.
Mitev
V
V
Houdebine
L M
LM
Coulomb
B
B
D000328:Adult; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002478:Cells, Cultured; D002853:Chromatography, Liquid; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D005260:Female; D005347:Fibroblasts / Q000201:enzymology; D006801:Humans; D015151:Immunoblotting; D007211:Indoles / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D004676:Myelin Basic Protein / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D012867:Skin / Q000166:cytology / Q000201:enzymology*
D004791:Enzyme Inhibitors; D007211:Indoles; D008301:Maleimides; D004676:Myelin Basic Protein; D004815:Epidermal Growth Factor; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C070515:bisindolylmaleimide I