Lind Simon, Hoffmann Dagny Olofsson, Forsman Huamei, Dahlgren Claes
Department of Rheumatology and Inflammation Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Sweden.
Department of Rheumatology and Inflammation Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Sweden.
Cell Signal. 2022 Feb;90:110208. doi: 10.1016/j.cellsig.2021.110208. Epub 2021 Nov 29.
A novel receptor crosstalk activation mechanism, through which signals generated by the agonist-occupied P2YR (the neutrophil receptor for ATP) activate allosterically modulated free fatty acid 2 receptor (FFA2R) without the involvement of any FFA2R agonist, was used to determine the inhibitor profiles of two earlier-described, FFA2R-specific antagonists, CATPB and GLPG0974. These antagonists have been shown to have somewhat different receptor-interaction characteristics at the molecular/functional level, although both are recognized by the orthosteric site in FFA2R. The antagonists inhibited neutrophil activation induced by ATP, an activation occurred only in the presence of either of the two positive allosteric FFA2R modulators (PAMs) AZ1729 and Cmp58. No neutrophil activation was induced by either AZ1729 or Cmp58 alone, whereas together they acted as co-agonistic PAMs and activated the superoxide-generating NADPH-oxidase in neutrophils. This response was inhibited by CATPB but not by GLPG0974. In contrast, GLPG0974 acted as a positive modulator, increasing the potency, albeit not the efficacy, of the co-agonistic PAMs. GLPG0974 also altered signaling downstream of FFA2R when activated by the co-agonistic PAMs. In the presence of GLPG0974, the response of neutrophils induced by the co-agonistic PAMs included an increase in the cytosolic concentration of free calcium ions (Ca), and this effect was reciprocal in that GLPG0974 triggered an increase in intracellular Ca, demonstrating that GLPG0974 acted as an FFA2R agonist. In summary, by studying the effects of the FFA2R ligand GLPG0974 on neutrophil activation induced by the co-agonists AZ1729 + Cmp58, we show that GLPG0974 is not only an FFA2R antagonist, but also displays agonistic and positive FFA2R-modulating functions that affect NADPH-oxidase activity and alter the receptor-downstream signaling induced by the co-agonistic PAMs.
一种新型的受体串扰激活机制被用于确定两种先前描述的FFA2R特异性拮抗剂CATPB和GLPG0974的抑制谱。在该机制中，由激动剂占据的P2YR（ATP的中性粒细胞受体）产生的信号可别构调节游离脂肪酸2受体（FFA2R）的活性，而无需任何FFA2R激动剂的参与。尽管这两种拮抗剂都能被FFA2R的正构位点识别，但在分子/功能水平上，它们显示出有所不同的受体相互作用特征。这些拮抗剂抑制了ATP诱导的中性粒细胞激活，这种激活仅在两种正别构FFA2R调节剂（PAM）AZ1729和Cmp58存在时发生。单独使用AZ1729或Cmp58均未诱导中性粒细胞激活，而它们共同作用时作为协同激动性PAM，激活中性粒细胞中产生超氧化物的NADPH氧化酶。这种反应被CATPB抑制，但未被GLPG0974抑制。相反，GLPG0974作为一种正调节剂，增加了协同激动性PAM的效力，尽管没有增加其效能。当被协同激动性PAM激活时，GLPG0974还改变了FFA2R下游的信号传导。在GLPG0974存在的情况下，协同激动性PAM诱导的中性粒细胞反应包括细胞溶质中游离钙离子（Ca）浓度的增加，并且这种效应是相互的，即GLPG0974引发细胞内Ca的增加，表明GLPG0974作为FFA2R激动剂发挥作用。总之，通过研究FFA2R配体GLPG0974对协同激动剂AZ1729 + Cmp58诱导的中性粒细胞激活的影响，我们表明GLPG0974不仅是一种FFA2R拮抗剂，而且还具有激动性和正性FFA2R调节功能，可影响NADPH氧化酶活性并改变协同激动性PAM诱导的受体下游信号传导。
