Dephosphorylation of receptor tyrosine kinases as target of regulation by radiation, oxidants or alkylating agents.
Several non-physiologic agents such as radiation, oxidants and alkylating agents induce ligand-independent activation of numerous receptor tyrosine kinases (RTKs) and of protein tyrosine kinases at the inner side of the plasma membrane (e.g. Dévary et al., 1992; Sachsenmaier et al., 1994; Schieven et al., 1994; Coffer et al., 1995). Here we show additional evidence for the activation of epidermal growth factor receptor (EGFR), and we show activation of v-ErbB, ErbB2 and platelet-derived growth factor receptor. As a common principle of action the inducing agents such as UVC, UVB, UVA, hydrogen peroxide and iodoacetamide inhibit receptor tyrosine dephosphorylation in a thiol-sensitive and, with the exception of the SH-alkylating agent, reversible manner. EGFR dephosphorylation can also be modulated by these non-physiologic agents in isolated plasma membranes in the presence of Triton X-100. Further, substrate (EGFR) and phosphatase have been separated: a membrane preparation of cells that have been treated with epidermal growth factor (EGF) and whose dephosphorylating enzymes have been permanently destroyed by iodoacetamide can be mixed with a membrane preparation from untreated cells which re-establishes EGFR dephosphorylation. This dephosphorylation can be modulated in vitro by UV and thiol agents. We conclude that RTKs exhibit significant spontaneous protein kinase activity; several adverse agents target (an) essential SH-group(s) carried by (a) membrane-bound protein tyrosine phosphatase(s).
Knebel
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Forschungszentrum Karlsruhe, Institut für Genetik, Universität Karlsruhe, Germany.
Rahmsdorf
H J
HJ
Ullrich
A
A
Herrlich
P
P
D000111:Acetylcysteine / Q000494:pharmacology; D000477:Alkylating Agents / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007460:Iodoacetamide / Q000494:pharmacology; D017895:Manganese Compounds / Q000494:pharmacology; D018739:Oncogene Proteins v-erbB / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology; D010087:Oxides / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors / Q000502:physiology; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D017978:Receptors, Growth Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014466:Ultraviolet Rays; D014638:Vanadates / Q000494:pharmacology
D000477:Alkylating Agents; D004791:Enzyme Inhibitors; D017895:Manganese Compounds; D018739:Oncogene Proteins v-erbB; D016877:Oxidants; D010087:Oxides; D017978:Receptors, Growth Factor; C048856:permanganic acid; D014638:Vanadates; D006861:Hydrogen Peroxide; D066246:ErbB Receptors; D020794:Receptor Protein-Tyrosine Kinases; D017027:Protein Tyrosine Phosphatases; D000111:Acetylcysteine; D007460:Iodoacetamide