Abstract
A pituitary adenylate cyclase-activating polypeptide (PACAP)-specific receptor, PAC1R, is coupled with multiple signal transduction pathways including stimulation of adenylate cyclase, phospholipase C and extracellular-signal regulated kinase (ERK)1/2. PAC1R has been shown to exert its long-lasting and potent signals via β-arrestin1 and β-arrestin2. However, the precise roles of the two β-arrestin isoforms in PACAP-PAC1R signaling remain unclear. Here we examined the interaction between the two β-arrestin isoforms and PAC1R, β-arrestin-dependent PAC1R subcellular localization and ERK1/2 activation. Upon PACAP stimulation, although PAC1R similarly interacted with β-arrestin1 and β-arrestin2 in HEK293T cells, the complex of PAC1R and β-arrestin2 was translocated from the cell surface into cytosol, but that of β-arrestin1 remained in the cell surface regions in HeLa cells and mouse primary cultured neurons. Silencing of β-arrestin2 blocked PACAP-induced PAC1R internalization and ERK1/2 phosphorylation, but silencing of β-arrestin1 increased ERK1/2 phosphorylation. These results show that β-arrestin1 and β-arrestin2 exert differential actions on PAC1R internalization and PAC1R-dependent ERK1/2 activation, and suggest that the two β-arrestin isoforms may be involved in fine and precise tuning of the PAC1R signaling pathways.
Highlights
Pituitary adenylate cyclase-activating polypeptide (PACAP) [1] is a multifunctional neuropeptide expressed in the central and peripheral nervous systems and acts as a neurotransmitter and neurotrophic factor via three subtypes of G protein-coupled receptors: a PACAP-preferring (PAC1) receptor (PAC1R) and two vasoactive intestinal polypeptide (VIP)-shared (VPAC1 and VPAC2) receptors [1, 2]
We examined the roles of β-arrestin1 and βarrestin2 involved in the PACAP-stimulated PAC1R-mediated prolonged ERK1/2 activation relevant to the PAC1R internalization
We showed that silencing of βarrestin2 significantly reduced PACAP-induced PAC1R internalization and prolonged ERK1/ 2 activation, but silencing of β-arrestin1 did not affect PAC1R internalization and rather increased ERK1/2 phosphorylation
Summary
Pituitary adenylate cyclase-activating polypeptide (PACAP) [1] is a multifunctional neuropeptide expressed in the central and peripheral nervous systems and acts as a neurotransmitter and neurotrophic factor via three subtypes of G protein-coupled receptors: a PACAP-preferring (PAC1) receptor (PAC1R) and two vasoactive intestinal polypeptide (VIP)-shared (VPAC1 and VPAC2) receptors [1, 2]. These funders have the role of data collection and analysis, decision to publish and preparation of the manuscript.
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