Domazet Ivana, Holleran Brian J, Richard Alexandra, Vandenberghe Camille, Lavigne Pierre, Escher Emanuel, Leduc Richard, Guillemette Gaétan
Department of Pharmacology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
Department of Pharmacology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
Mol Pharmacol. 2015 Jun;87(6):982-95. doi: 10.1124/mol.114.097337. Epub 2015 Mar 25.
The octapeptide angiotensin II (AngII) exerts a variety of cardiovascular effects through the activation of the AngII type 1 receptor (AT1), a G protein-coupled receptor. The AT1 receptor engages and activates several signaling pathways, including heterotrimeric G proteins Gq and G12, as well as the extracellular signal-regulated kinases (ERK) 1/2 pathway. Additionally, following stimulation, βarrestin is recruited to the AT1 receptor, leading to receptor desensitization. It is increasingly recognized that specific ligands selectively bind and favor the activation of some signaling pathways over others, a concept termed ligand bias or functional selectivity. A better understanding of the molecular basis of functional selectivity may lead to the development of better therapeutics with fewer adverse effects. In the present study, we developed assays allowing the measurement of six different signaling modalities of the AT1 receptor. Using a series of AngII peptide analogs that were modified in positions 1, 4, and 8, we sought to better characterize the molecular determinants of AngII that underlie functional selectivity of the AT1 receptor in human embryonic kidney 293 cells. The results reveal that position 1 of AngII does not confer functional selectivity, whereas position 4 confers a bias toward ERK signaling over Gq signaling, and position 8 confers a bias toward βarrestin recruitment over ERK activation and Gq signaling. Interestingly, the analogs modified in position 8 were also partial agonists of the protein kinase C (PKC)-dependent ERK pathway via atypical PKC isoforms PKCζ and PKCι.
八肽血管紧张素II（AngII）通过激活1型血管紧张素II受体（AT1）发挥多种心血管效应，AT1是一种G蛋白偶联受体。AT1受体参与并激活多种信号通路，包括异源三聚体G蛋白Gq和G12，以及细胞外信号调节激酶（ERK）1/2通路。此外，刺激后，β抑制蛋白被招募到AT1受体，导致受体脱敏。人们越来越认识到，特定配体选择性结合并优先激活某些信号通路而非其他通路，这一概念称为配体偏向性或功能选择性。更好地理解功能选择性的分子基础可能会开发出副作用更少的更好疗法。在本研究中，我们开发了可测量AT1受体六种不同信号传导方式的检测方法。使用一系列在第1、4和8位进行修饰的AngII肽类似物，我们试图更好地表征AngII的分子决定因素，这些因素是人类胚胎肾293细胞中AT1受体功能选择性的基础。结果表明，AngII的第1位不赋予功能选择性，而第4位赋予ERK信号传导相对于Gq信号传导的偏向性，第8位赋予β抑制蛋白招募相对于ERK激活和Gq信号传导的偏向性。有趣的是，在第8位修饰的类似物也是通过非典型PKC亚型PKCζ和PKCι的蛋白激酶C（PKC）依赖性ERK途径的部分激动剂。
