Epidermal Growth Factor Stimulates Mitogen-Activated Protein Kinase by a PKC-Dependent Pathway in Human Keratinocytes

• Published in: Biochemical and biophysical research communications 1995-03, Vol.208 (1), p.245-252
• Main Authors: Mitev, V., Lepanse, R., Coulomb, B., Miteva, L., Houdebine, L.M.
• Format: Article
• Language: English
• Subjects: Biochemistry, Molecular Biology; Calcium-Calmodulin-Dependent Protein Kinases - metabolism; Cells, Cultured; Chromatography, High Pressure Liquid; Cytosol - enzymology; Epidermal Growth Factor - pharmacology; Humans; Immunoblotting; Keratinocytes - drug effects; Keratinocytes - enzymology; Kinetics; Life Sciences; Myelin Basic Protein - isolation & purification; Myelin Basic Protein - metabolism; Phosphorylation; Protein Kinase C - metabolism; Skin - enzymology
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1006/bbrc.1995.1330

Epidermal growth factor (EGF),20 ng/ml,stimulated myelin basic protein (MBP) phosphorylation in crude extracts from human keratinocyte primary cultures. In order to identify the involved kinases, we separated by fast protein liquid chromatography proteins participating in MBP phosphorylation. We detected three MBP kinase activities in the keratinocyte crude extracts. The first MBP kinase activity was the only one stimulated by EGF and reacted with anti-mitogen-activated protein kinase (MAPK) antiserum recognising p42 mapk and p44 mapk isoforms. However, when protein kinase C (PKC) was either inhibited by the PKC inhibitor GF 109203X or depleted by a prolonged TPA treatment, the stimulation of MBP phosphorylation by EGF was strongly inhibited. The second MBP kinase activity eluted was due to a PKC isoform reacting with an anti-PKC ζ antibody, and the third was not identified. With this work, we have thus shown that, in human keratinocytes, EGF activates MAPK activity by a PKC-dependent pathway.