Protein phosphatase 2A mediates resensitization of the neurokinin 1 receptor

• Published in: American Journal of Physiology: Cell Physiology 2011-10, Vol.301 (4), p.C780-C791
• Main Authors: Murphy, Jane E, Roosterman, Dirk, Cottrell, Graeme S, Padilla, Benjamin E, Feld, Micha, Brand, Eva, Cedron, Wendy J, Bunnett, Nigel W, Steinhoff, Martin
• Format: Article
• Language: English
• Subjects: Bacteriocins; Binding sites; Cell Membrane - physiology; Cells; Gene Expression Regulation - physiology; Humans; Indoles - pharmacology; Maleimides - pharmacology; Peptides; Phosphorylation; Protein Isoforms; Protein Kinase C - antagonists & inhibitors; Protein Phosphatase 2 - genetics; Protein Phosphatase 2 - metabolism; Proteins; Receptors and Signal Transduction; Receptors, G-Protein-Coupled; Receptors, Neurokinin-1 - genetics; Receptors, Neurokinin-1 - metabolism; Signal Transduction
• ISSN: 0363-6143; 1522-1563
• DOI: 10.1152/ajpcell.00096.2011

Activated G protein-coupled receptors (GPCRs) are phosphorylated and interact with β-arrestins, which mediate desensitization and endocytosis. Endothelin-converting enzyme-1 (ECE-1) degrades neuropeptides in endosomes and can promote recycling. Although endocytosis, dephosphorylation, and recycling are accepted mechanisms of receptor resensitization, a large proportion of desensitized receptors can remain at the cell surface. We investigated whether reactivation of noninternalized, desensitized (phosphorylated) receptors mediates resensitization of the substance P (SP) neurokinin 1 receptor (NK(1)R). Herein, we report a novel mechanism of resensitization by which protein phosphatase 2A (PP2A) is recruited to dephosphorylate noninternalized NK(1)R. A desensitizing concentration of SP reduced cell-surface SP binding sites by only 25%, and SP-induced Ca(2+) signals were fully resensitized before cell-surface binding sites started to recover, suggesting resensitization of cell-surface-retained NK(1)R. SP induced association of β-arrestin1 and PP2A with noninternalized NK(1)R. β-Arrestin1 small interfering RNA knockdown prevented SP-induced association of cell-surface NK(1)R with PP2A, indicating that β-arrestin1 mediates this interaction. ECE-1 inhibition, by trapping β-arrestin1 in endosomes, also impeded SP-induced association of cell-surface NK(1)R with PP2A. Resensitization of NK(1)R signaling required both PP2A and ECE-1 activity. Thus, after stimulation with SP, PP2A interacts with noninternalized NK(1)R and mediates resensitization. PP2A interaction with NK(1)R requires β-arrestin1. ECE-1 promotes this process by releasing β-arrestin1 from NK(1)R in endosomes. These findings represent a novel mechanism of PP2A- and ECE-1-dependent resensitization of GPCRs.