A Chemogenetic Platform for Spatio-temporal Control of β-arrestin Translocation and Signaling at G protein-Coupled Receptors

Although ligand-activated GPCRs induce both G-protein and β-arrestin dependent signaling, gaining precise spatio-temporal control of β-arrestin signaling has proven elusive. Here we describe a platform for specifically activating β-arrestin-dependent signaling in situ. The platform, which we have dubbed GA-PAIR (GPCR/β-Arrestin-Plant protein and Abscisic acid Induced Recruitment), can be controlled by the inert phytochemical S-(+)-abscisic acid (ABA). ABA induces interaction between ABI1 (ABA Insensitive 1) and PYL1 (Pyrabactin Resistance (PYR) 1-Like), two plant proteins with no mammalian counterparts. We fused ABI to the engineered human muscarinic M3 G protein-coupled receptor (hM3Dq) and PYL1 to β-arrestin2. Addition of ABA induced rapid and nearly complete translocation of the PYL-β-arrestin fusion protein and, importantly, induced both ERK and Akt signaling. Photo-uncaging a new photo-caged ABA analogue allowed us to gain relatively precise spatio-temporal control over β-arrestin translocation. Because GA-PAIR facilitates the exclusive activation of endogenous β-arrestin signaling pathways in the absence of a GPCR ligand or G protein, the GA-PAIR system will facilitate deconvoluting GPCR signaling in situ.