TY - JOUR

T1 - Insights into agonist-elicited activation of the human glucose-dependent insulinotropic polypeptide receptor

AU - Yuliantie, Elita

AU - van der Velden, Wijnand J.C.

AU - Labroska, Viktorija

AU - Dai, Antao

AU - Zhao, Fenghui

AU - Darbalaei, Sanaz

AU - Deganutti, Giuseppe

AU - Xu, Tongyang

AU - Zhou, Qingtong

AU - Yang, Dehua

AU - Rosenkilde, Mette M.

AU - Sexton, Patrick M.

AU - Wang, Ming Wei

AU - Wootten, Denise

N1 - Publisher Copyright: © 2021

PY - 2021

Y1 - 2021

N2 - Glucose-dependent insulinotropic polypeptide (GIP) and its receptor (GIPR) are part of the incretin system that regulates glucose homeostasis. A series of GIPR residues putatively important for ligand binding and receptor activation were mutated and pharmacologically evaluated using GIPR selective agonists in cAMP accumulation, ERK1/2 phosphorylation (pERK1/2) and β-arrestin 2 recruitment assays. The impact of mutation on ligand efficacy was determined by operational modelling of experimental data for each mutant, with results mapped onto the full-length, active-state GIPR structure. Two interaction networks, comprising transmembrane helix (TM) 7, TM1 and TM2, and extracellular loop (ECL) 2, TM5 and ECL3 were revealed, respectively. Both networks were critical for Gαs-mediated cAMP accumulation and the recruitment of β-arrestin 2, however, cAMP response was more sensitive to alanine substitution, with most mutated residues displaying reduced signaling. Unlike the other two assays, activation of ERK1/2 was largely independent of the network involving ECL2, TM5 and ECL3, indicating that pERK1/2 is at least partially distinct from Gαs or β-arrestin pathways and this network is also crucial for potential biased agonism at GIPR. Collectively, our work advances understanding of the structure–function relationship of GIPR and provides a framework for the design and/or interpretation of GIP analogues with unique signaling profiles.

AB - Glucose-dependent insulinotropic polypeptide (GIP) and its receptor (GIPR) are part of the incretin system that regulates glucose homeostasis. A series of GIPR residues putatively important for ligand binding and receptor activation were mutated and pharmacologically evaluated using GIPR selective agonists in cAMP accumulation, ERK1/2 phosphorylation (pERK1/2) and β-arrestin 2 recruitment assays. The impact of mutation on ligand efficacy was determined by operational modelling of experimental data for each mutant, with results mapped onto the full-length, active-state GIPR structure. Two interaction networks, comprising transmembrane helix (TM) 7, TM1 and TM2, and extracellular loop (ECL) 2, TM5 and ECL3 were revealed, respectively. Both networks were critical for Gαs-mediated cAMP accumulation and the recruitment of β-arrestin 2, however, cAMP response was more sensitive to alanine substitution, with most mutated residues displaying reduced signaling. Unlike the other two assays, activation of ERK1/2 was largely independent of the network involving ECL2, TM5 and ECL3, indicating that pERK1/2 is at least partially distinct from Gαs or β-arrestin pathways and this network is also crucial for potential biased agonism at GIPR. Collectively, our work advances understanding of the structure–function relationship of GIPR and provides a framework for the design and/or interpretation of GIP analogues with unique signaling profiles.

KW - Arrestin

KW - cAMP

KW - ERK

KW - G protein-coupled receptor

KW - Glucose-dependent insulinotropic polypeptide receptor

KW - GPCR structure–function relationship

U2 - 10.1016/j.bcp.2021.114715

DO - 10.1016/j.bcp.2021.114715

M3 - Journal article

C2 - 34339714

AN - SCOPUS:85111973797

VL - 192

JO - Biochemical Pharmacology

JF - Biochemical Pharmacology

SN - 0006-2952

M1 - 114715

ER -