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标题：Experimental and computational analysis of biased agonism on full-length and a C-terminally truncated adenosine A2A receptor
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作者：Gemma Navarro ; Angel Gonzalez ; Stefano Campanacci 等
期刊名称：Computational and Structural Biotechnology Journal
印刷版ISSN：2001-0370
出版年度：2020
卷号：18
页码：2723-2732
DOI：10.1016/j.csbj.2020.09.028
出版社：Computational and Structural Biotechnology Journal
摘要：Biased agonism, the ability of agonists to differentially activate downstream signaling pathways by stabilizing specific receptor conformations, is a key issue for G protein-coupled receptor (GPCR) signaling. The C-terminal domain might influence this functional selectivity of GPCRs as it engages G proteins, GPCR kinases, β-arrestins, and several other proteins. Thus, the aim of this paper is to compare the agonist-dependent selectivity for intracellular pathways in a heterologous system expressing the full-length (A 2A R) and a C-tail truncated (A 2A Δ40 R lacking the last 40 amino acids) adenosine A 2A receptor, a GPCR that is already targeted in Parkinson’s disease using a first-in-class drug. Experimental data such as ligand binding, cAMP production, β-arrestin recruitment, ERK1/2 phosphorylation and dynamic mass redistribution assays, which correspond to different aspects of signal transduction, were measured upon the action of structurally diverse compounds (the agonists adenosine, NECA, CGS-21680, PSB-0777 and LUF-5834 and the SCH-58261 antagonist) in cells expressing A 2A R and A 2A Δ40 R. The results show that taking cAMP levels and the endogenous adenosine agonist as references, the main difference in bias was obtained with PSB-0777 and LUF-5834. The C-terminus is dispensable for both G-protein and β-arrestin recruitment and also for MAPK activation. Unrestrained molecular dynamics simulations, at the μs timescale, were used to understand the structural arrangements of the binding cavity, triggered by these chemically different agonists, facilitating G protein binding with different efficacy.
关键词：G protein coupled receptors ; Adenosine A_2A receptor ; Functional selectivity ; G protein binding ; β-Arrestin recruitment ; Molecular dynamic simulations