Tethering of the platelet-derived growth factor beta receptor to G-protein-coupled receptors. A novel platform for integrative signaling by these receptor classes in mammalian cells

• Published in: The Journal of biological chemistry 2001-07, Vol.276 (30), p.28578-28585
• Main Authors: Alderton, F, Rakhit, S, Kong, K C, Palmer, T, Sambi, B, Pyne, S, Pyne, N J
• Format: Article
• Language: English
• Subjects: Cell Line; Cells, Cultured; Dose-Response Relationship, Drug; Enzyme Activation; Enzyme Inhibitors - pharmacology; Humans; Lysophospholipids; Mitogen-Activated Protein Kinase 1; Myc-tagged endothelial differentiation gene 1; p42 MAP kinase; p44 MAP kinase; Pertussis Toxin; Phosphorylation; Platelet-Derived Growth Factor - metabolism; platelet-derived growth factor receptor ^b; Precipitin Tests; Protein Binding; Receptor, Platelet-Derived Growth Factor beta - chemistry; Receptor, Platelet-Derived Growth Factor beta - metabolism; Receptors, Cell Surface - chemistry; Recombinant Proteins - metabolism; Signal Transduction; Sphingosine - analogs & derivatives; Sphingosine - metabolism; Transfection; Tyrphostins - pharmacology; Virulence Factors, Bordetella - pharmacology
• ISSN: 0021-9258
• DOI: 10.1074/jbc.M102771200

Here we provide evidence to show that the platelet-derived growth factor beta receptor is tethered to endogenous G-protein-coupled receptor(s) in human embryonic kidney 293 cells. The tethered receptor complex provides a platform on which receptor tyrosine kinase and G-protein-coupled receptor signals can be integrated to produce more efficient stimulation of the p42/p44 mitogen-activated protein kinase pathway. This was based on several lines of evidence. First, we have shown that pertussis toxin (which uncouples G-protein-coupled receptors from inhibitory G-proteins) reduced the platelet-derived growth factor stimulation of p42/p44 mitogen-activated protein kinase. Second, transfection of cells with inhibitory G-protein alpha subunit increased the activation of p42/p44 mitogen-activated protein kinase by platelet-derived growth factor. Third, platelet-derived growth factor stimulated the tyrosine phosphorylation of the inhibitory G-protein alpha subunit, which was blocked by the platelet-derived growth factor kinase inhibitor, tyrphostin AG 1296. We have also shown that the platelet-derived growth factor beta receptor forms a tethered complex with Myc-tagged endothelial differentiation gene 1 (a G-protein-coupled receptor whose agonist is sphingosine 1-phosphate) in cells co-transfected with these receptors. This facilitates platelet-derived growth factor-stimulated tyrosine phosphorylation of the inhibitory G-protein alpha subunit and increases p42/p44 mitogen-activated protein kinase activation. In addition, we found that G-protein-coupled receptor kinase 2 and beta-arrestin I can associate with the platelet-derived growth factor beta receptor. These proteins play an important role in regulating endocytosis of G-protein-coupled receptor signal complexes, which is required for activation of p42/p44 mitogen-activated protein kinase. Thus, platelet-derived growth factor beta receptor signaling may be initiated by G-protein-coupled receptor kinase 2/beta-arrestin I that has been recruited to the platelet-derived growth factor beta receptor by its tethering to a G-protein-coupled receptor(s). These results provide a model that may account for the co-mitogenic effect of certain G-protein-coupled receptor agonists with platelet-derived growth factor on DNA synthesis.