Neomycin is a platelet-derived growth factor (PDGF) antagonist that allows discrimination of PDGF alpha- and beta-receptor signals in cells expressing both receptor types.
The aminoglycoside neomycin has recently been found to affect certain platelet-derived growth factor (PDGF) responses in C3H/10T1/2 C18 fibroblasts. Using porcine aortic endothelial cells transfected with PDGF alpha- or beta-receptors, we explored the possibility that neomycin interferes with the interaction between the different PDGF isoforms and their receptors. We found that neomycin (5 mM) inhibited the binding of 125I-PDGF-BB to the alpha-receptor with only partial effect on the binding of 125I-PDGF-AA; in contrast, the binding of 125I-PDGF-BB to the beta-receptor was not affected by the aminoglycoside. Scatchard analyses showed that neomycin (5 mM) decreased the number of binding sites for PDGF-BB on alpha-receptor-expressing cells by 87%. Together with cross-competition studies with 125I-labeled PDGF homodimers, the effect of neomycin indicates that PDGF-AA and PDGF-BB bind to both common and unique structures on the PDGF alpha-receptor. Neomycin specifically inhibited the autophosphorylation of the alpha-receptor by PDGF-BB, with less effect on the phosphorylation induced by PDGF-AA and no effect on the phosphorylation of the beta-receptor by PDGF-BB. Thus, neomycin is a PDGF isoform- and receptor-specific antagonist that provides a possibility to compare the signal transduction pathways of alpha- and beta-receptors in cells expressing both receptor types. This approach was used to show that activation of PDGF beta-receptors by PDGF-BB mediated a chemotactic response in human fibroblasts, whereas activation of alpha-receptors by the same ligand inhibited chemotaxis.
Vassbotn
F S
FS
Ludwig Institute for Cancer Research, Biomedical Center, Uppsala, Sweden.
Ostman
A
A
Siegbahn
A
A
Holmsen
H
H
Heldin
C H
CH
D000617:Aminoglycosides / Q000494:pharmacology; D000818:Animals; D000906:Antibodies; D001667:Binding, Competitive; D002460:Cell Line; D002633:Chemotaxis / Q000187:drug effects*; D004730:Endothelium, Vascular / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D051379:Mice; D008954:Models, Biological; D009355:Neomycin / Q000494:pharmacology*; D010982:Platelet-Derived Growth Factor / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D017479:Receptors, Platelet-Derived Growth Factor; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology; D013552:Swine; D014162:Transfection
D000617:Aminoglycosides; D000906:Antibodies; D010982:Platelet-Derived Growth Factor; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; D017479:Receptors, Platelet-Derived Growth Factor; D009355:Neomycin