Translocation of protein kinase C to membranes induced by TNF does not cause the inhibition of EGF binding to human wish cells.
Tumor necrosis factor (TNF) caused an inhibition of 125I-labeled epidermal growth factor [( 125I]EGF) binding to its receptors of human amniotic (WISH) cells at 5 min after addition of TNF, which reached a maximal level (60-70% reduction) after 15-30 min and declined thereafter. TNF also induced a translocation of protein kinase C activity from the cytosol to the membrane, which peaked at 45-60 min after addition of TNF and almost returned to basal level at 120 min. Furthermore, prolonged incubation of WISH cells with 12-O-tetradecanoylphorbol 13 acetate (TPA) diminished the TPA effect on the inhibition of EGF binding to the cells due to the desensitization of protein kinase C; however, TNF still reduced the EGF binding to the cells pretreated with TPA for a long time. These results indicate that although TNF causes the translocation of protein kinase C to the membrane, activation of protein kinase C is not required for TNF to induce a decrease in EGF binding to the cells.
Katoh
T
T
Department of Biochemistry, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan.
Karasaki
Y
Y
Hirano
H
H
Gotoh
S
S
Higashi
K
K
D000650:Amnion / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D002478:Cells, Cultured; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology; D004815:Epidermal Growth Factor / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D011493:Protein Kinase C / Q000235:genetics*; D014178:Translocation, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D014409:Tumor Necrosis Factor-alpha; D004815:Epidermal Growth Factor; D011493:Protein Kinase C