RT Journal Article
SR Electronic
T1 Signals Generated by Neutrophil Receptors for Danger Molecules Transactivate Allosterically Modulated FFA2R: Distinct response patterns are mediated by modulators recognized by different allosteric receptor sites
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2022.04.29.489985
DO 10.1101/2022.04.29.489985
A1 Simon Lind
A1 Kenneth L. Granberg
A1 Huamei Forsman
A1 Claes Dahlgren
YR 2022
UL http://biorxiv.org/content/early/2022/04/29/2022.04.29.489985.abstract
AB Positive allosteric modulators for free fatty acid receptor 2 (FFA2R/GPR43), that affect receptor function through binding to two distinct allosteric binding sites, were used to determine the correlation between the responses induced in neutrophils by two distinct activation modes; FFA2R was activated either by the orthosteric agonist propionate or by a receptor transactivation mechanism that activated FFA2R from the cytosolic side of the neutrophil plasma membrane by signals generated by the neutrophil PAFR (receptor for platelet activating factor), P2Y2R (receptor for ATP), FPR1 (receptor for fMLF) and FPR2 (receptor for WKYMVM). We show that the transactivation signals that activate FFA2R in the absence of any orthosteric agonist were generated downstream of the signaling G protein that couple to PAFR and P2Y2R. This transactivation of allosterically modulated FFA2Rs, by signals generated by PAFR/P2Y2R, represents a novel mechanism by which a G protein coupled receptor can be activated. Weak correlations were obtained when the FFA2R activity was induced by the transactivation signals generated by PAFRs and P2Y2Rs were compared with the FFA2R activity induced by the orthosteric agonist propionate. Comparison of the responses for each allosteric modulator revealed that the ratio values, calculated from the peak values of the ATP and propionate responses, varied from 0.2 to 1. Depending on the allosteric modulator, the response induced by the two different mechanisms (orthosteric activation and receptor transactivation, respectively), was equal or the propionate response was more pronounced. Importantly, we conclude that FFA2R activation from outside (orthosteric activation) and inside (receptor cross-talk/transactivation) can be selectively affected by an allosteric FFA2R modulator.The allosterically modulated FFA2R is transactivated by signals generated by other GPCRs.The PAF and ATP receptors transactivate FFA2R from the cytosolic side of the membrane.The mechanisms that regulates activation of FFA2R from outside and inside differ.Competing Interest StatementThe authors have declared no competing interest.CATPB(S)-3-(2-(3-chlorophenyl)acetamido)-4-(4-(trifluoromethyl)-phenyl)butanoic acid an FFA2R antagonist/inverse agonist;CLchemiluminescence;Cmp1(R)-3-benzyl-4-(cyclopropyl(4-(2,5-dichlorophenyl)thiazol-2-yl)amino)-4-oxobutanoic acid a small molecule orthosteric FFA2R agonist;Cmp58an allosteric FFA2R modulator;AZ1729an FFA2R modulator;FFA2Rfree fatty acid receptor 2;GPCRG-protein coupled receptor;HRPhorse radish peroxidase;nsno significant difference;KRGKrebs-Ringer Glucose phosphate buffer ;ROSreactive oxygen species;TNF-αtumor necrosis factor α