Institut des Maladies Métaboliques et Cardiovasculaires, Université Toulouse III Paul Sabatier, Centre Hospitalier Universitaire de Toulouse, France.
Curr Pharm Des. 2012;18(2):128-44. doi: 10.2174/138161212799040466.
Cell surface G protein-coupled receptors (GPCRs) drive numerous signaling pathways involved in the regulation of a broad range of physiologic processes. Today, they represent the largest target for modern drugs development with potential application in all clinical fields. Recently, the concept of "ligand-directed trafficking" has led to a conceptual revolution in pharmacological theory, thus opening new avenues for drug discovery. Accordingly, GPCRs do not function as simple on-off switch but rather as filters capable of selecting the activation of specific signals and thus generating texture responses to ligands, a phenomenon often referred to as ligand-biased signaling. Also, one challenging task today remains optimization of pharmacological assays with increased sensitivity so to better appreciate the inherent texture of ligands. However, considering that a single receptor has pleiotropic signaling properties and that each signal can crosstalk at different levels, biased activity remains thus difficult to evaluate. One strategy to overcome these limitations would be examining the initial steps following receptor activation. Even, if some G protein independent functions have been recently described, heterotrimeric G protein activation remains a general hallmark for all GPCRs families and the first cellular event subsequent to agonist binding to the receptor. Herein, we review the different methodologies classically used or recently developed to monitor G protein activation and discussed them in the context of G protein biased-ligands.
细胞表面 G 蛋白偶联受体 (GPCR) 驱动着众多参与调节广泛生理过程的信号通路。如今，它们是现代药物开发的最大靶点，具有在所有临床领域应用的潜力。最近，“配体导向的运输”的概念引发了药理学理论的概念革命，从而为药物发现开辟了新途径。因此，GPCR 并非简单的开/关开关，而是能够选择激活特定信号的滤波器，从而对配体产生纹理反应，这种现象通常被称为配体偏向信号。此外，当今仍然面临着一项具有挑战性的任务，即优化具有更高灵敏度的药理学测定法，以便更好地了解配体的固有纹理。然而，考虑到单个受体具有多种信号转导特性，并且每个信号都可以在不同水平上相互作用，因此偏向活性仍然难以评估。克服这些限制的一种策略是检查受体激活后的初始步骤。即使最近描述了一些 G 蛋白非依赖性功能，但异三聚体 G 蛋白的激活仍然是所有 GPCR 家族的通用标志，也是激动剂与受体结合后随后发生的第一个细胞事件。在此，我们综述了经典或最近开发的用于监测 G 蛋白激活的不同方法，并在 G 蛋白偏向配体的背景下对它们进行了讨论。
