Differences in β‐arrestin dependent signaling by PAR2 and NK1R are directed by their C terminal tails

Abstract

PAR2 and NK1R are 7 transmembrane receptors (7TMRs), which signal by Gαq leading to Ca2+ release and protein kinase C (PKC) activation. Both receptors are desensitized by β‐arrestin binding to their C termini. They can also activate ERK1/2 through β‐arrestin scaffolding complexes. They differ in ERK1/2 mediated physiological outcomes: cell migration versus proliferation. Using β‐arrestins, PAR2 activates cofilin, to promote chemotaxis. We hypothesized that the differences in β‐arrestin dependent signaling by 7TMRs can be attributed to how the molecular scaffolds bind the C‐tail of the receptors. Using wild type and C‐tail chimeras, we showed that the rate of desensitization, internalization, subcellular localization post endocytosis and ERK1/2 mediated responses depend on the nature of interaction of β‐arrestins with the C‐termini. BRET assays showed that PAR2 recruits both β‐arrestin 1/2 faster and with greater affinity than NK1R. We further show that initial Gαq signaling is necessary for β‐arrestin 1/2 recruitment to NK1R. PAR2 recruits β‐arrestin 1/2 even when Gαq pathway is blocked. Assays with C terminal phosphorylation mutants of PAR2 indicated that, phosphorylation of certain residues are necessary for β‐arrestin 1/2 recruitment. Phosphorylation at putative PKC sites determine stability of PAR2‐β‐arrestin 1/2 complex. This in turn ensures downstream cofilin activation and cell migration