Phosphorylation and desensitization of neurokinin-1 receptor expressed in epithelial cells.
A rat kidney epithelial cell line expressing the rat neurokinin-1 receptor (NK-1 R) was used to investigate the relationship between receptor phosphorylation and desensitization. Substance P (SP) maximally stimulated cellular inositol 1,4,5-trisphosphate (IP3) production 14-fold within 3 s, after which cellular IP3 levels rapidly diminished to near basal levels in the continuing presence of SP. SP also caused concentration-dependent phosphorylation of the NK-1R, and this effect was blocked by a receptor antagonist. Stimulation with 100 nM SP for as little as 2 s resulted in 90% desensitization of the receptor to restimulation by SP, and near-maximal receptor phosphorylation was observed at 5 s. Receptor desensitization was not affected by agents that affect protein kinase A. Phorbol 12-myristate 13-acetate (PMA) also caused phosphorylation and desensitization of the receptor but with slower kinetics and to a lesser extent than SP. PMA- but not SP-induced NK-1 R desensitization and phosphorylation were abolished by the protein kinase C inhibitor bisindolylmaleimide 1. The concentration-response curves for SP-stimulated IP3 signaling and desensitization were similar, but the curve for NK-1R phosphorylation was shifted to the right and was steeper, suggesting that the relationship between desensitization and phosphorylation is complex. These results show that both rapid homologous and rapid heterologous NK-1R desensitizations may be mediated by receptor phosphorylation but occur via distinct mechanisms with different kinetics and efficacies.
Vigna
S R
SR
Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D002461:Cell Line, Transformed; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000378:metabolism*; D015870:Gene Expression; D007163:Immunosorbent Techniques; D007211:Indoles / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007668:Kidney; D007700:Kinetics; D008301:Maleimides / Q000494:pharmacology; D064729:Neurokinin-1 Receptor Antagonists; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D051381:Rats; D018040:Receptors, Neurokinin-1 / Q000187:drug effects* / Q000235:genetics*; D015398:Signal Transduction / Q000187:drug effects; D013373:Substance P / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D004791:Enzyme Inhibitors; D007211:Indoles; D008301:Maleimides; D064729:Neurokinin-1 Receptor Antagonists; D018040:Receptors, Neurokinin-1; D015124:8-Bromo Cyclic Adenosine Monophosphate; D013373:Substance P; D015544:Inositol 1,4,5-Trisphosphate; D011493:Protein Kinase C; C088060:bisindolylmaleimide; D013755:Tetradecanoylphorbol Acetate