CXCL17 activates three MAS-related G protein-coupled receptors independently of its conserved C-terminal fragment

C-X-C motif chemokine ligand 17 (CXCL17) is a chemoattractant whose receptor remains controversial. While recent studies identified CXCL17 as an agonist of G protein-coupled receptor 25 (GPR25), it was also reported to activate MAS-related GPR family member X2 (MRGPRX2), a member of MAS-related G protein-coupled receptors (MRGPRs), though this finding has not yet been reproduced by other laboratories. In this study, we confirmed that micromolar concentrations of human CXCL17 activate human MRGPRX2 in transfected human embryonic kidney (HEK) 293T cells using a NanoLuc Binary Technology (NanoBiT)-based β-arrestin recruitment assay. We further demonstrated that human CXCL17 also activates MRGPRX1 and MAS1 among 10 human MRGPRs in the same assay. CXCL17 could also induce chemotactic movement of transfected HEK293T cells expressing MRGPRX2, MRGPRX1, or MAS1. However, removal of C-terminal residues from CXCL17 did not affect its activation of these three MRGPRs, even though this region is essential for GPR25 activation. These results suggest that CXCL17 activates MRGPRX2, MRGPRX1, and MAS1 through a mechanism distinct from GPR25 activation. Further investigation is needed to determine whether these MRGPRs mediate the in vivo functions of CXCL17.