Gabl Michael, Holdfeldt Andre, Sundqvist Martina, Lomei Jalal, Dahlgren Claes, Forsman Huamei
Department of Rheumatology and Inflammation Research, University of Gothenburg, Gothenburg, Sweden.
Department of Medical Cell Biology, Uppsala University, Sweden.
Biochem Pharmacol. 2017 Dec 1;145:114-122. doi: 10.1016/j.bcp.2017.08.018. Epub 2017 Aug 30.
G-protein coupled receptor (GPCR) biased agonism or functional selectivity has become an essential concept in GPCR research over the last years. Receptor-specific biased agonists selectively trigger one signaling pathway over another and induce a restricted/directed functional response. In this study, we aimed to characterize the concept of biased agonism for FPR2, a member of the formyl peptide receptor (FPR) subfamily of GPCRs. We show that the earlier described FPR2-activating pepducin F2Pal is a biased FPR2 agonist. The effects of F2Pal on neutrophil function differed in several aspects compared to those mediated by WKYMVM, a conventional FPR2-specific peptide agonist. Upon interaction with FPR2 expressed by neutrophils both F2Pal and WKYMVM activated the PLC-PIP-Ca signaling pathway and the superoxide-generating NADPH-oxidase, but only WKYMVM activated the receptor to recruit β-arrestin. The functional consequences linked to a lack of β-arrestin recruitment were further explored, and we demonstrate that FPR2 desensitization occurred independent of β-arrestin. Despite this, reactivation of desensitized receptors achieved through a disruption of the cytoskeleton and through a novel FPR2 cross-talk mechanism with P2YR (the ATP receptor) and PAFR (the receptor for PAF) differed between F2Pal-desensitized and WKYMVM-desensitized neutrophils. Further, the inability to recruit β-arrestin was found to be associated with a reduced rate of receptor internalization and impaired chemotaxis in neutrophils. In summary, we provide experimental evidence of biased agonism for FPR2 and our data disclose critical roles of β-arrestin in neutrophil chemotaxis and reactivation of desensitized receptors.
在过去几年中，G蛋白偶联受体（GPCR）偏向性激动作用或功能选择性已成为GPCR研究中的一个重要概念。受体特异性偏向性激动剂会选择性地触发一种信号通路而非另一种，并诱导有限的/定向的功能反应。在本研究中，我们旨在阐明GPCRs中甲酰肽受体（FPR）亚家族成员FPR2的偏向性激动作用概念。我们发现，先前描述的激活FPR2的肽导向激动剂F2Pal是一种偏向性FPR2激动剂。与传统的FPR2特异性肽激动剂WKYMVM介导的作用相比，F2Pal对中性粒细胞功能的影响在几个方面有所不同。与中性粒细胞表达的FPR2相互作用时，F2Pal和WKYMVM均激活了磷脂酶C - 磷脂酰肌醇 - 钙信号通路以及产生超氧化物的NADPH氧化酶，但只有WKYMVM激活受体以募集β - 抑制蛋白。我们进一步探讨了与缺乏β - 抑制蛋白募集相关的功能后果，并证明FPR2脱敏的发生与β - 抑制蛋白无关。尽管如此，通过破坏细胞骨架以及通过与P2YR（ATP受体）和PAFR（PAF受体）的新型FPR2串扰机制实现的脱敏受体再激活，在F2Pal脱敏的中性粒细胞和WKYMVM脱敏的中性粒细胞之间存在差异。此外，发现无法募集β - 抑制蛋白与中性粒细胞中受体内化速率降低和趋化性受损有关。总之，我们提供了FPR2偏向性激动作用的实验证据，我们的数据揭示了β - 抑制蛋白在中性粒细胞趋化性和脱敏受体再激活中的关键作用。
