The orphan G‐protein‐coupled receptor 75 signaling is activated by the chemokine CCL5

Abstract The chemokine CCL 5 prevents neuronal cell death mediated both by amyloid β, as well as the human immunodeficiency virus viral proteins gp120 and Tat. Because CCL 5 binds to CCR 5, CCR 3 and/or CCR 1 receptors, it remains unclear which of these receptors plays a role in neuroprotection. Indeed, CCL 5 also has neuroprotective activity in cells lacking these receptors. CCL 5 may bind to a G‐protein‐coupled receptor 75 ( GPR 75), which encodes for a 540 amino‐acid orphan receptor of the Gqα family. In this study, we have used SH ‐ SY 5Y human neuroblastoma cells to characterize whether CCL 5 could activate a Gq signaling through GPR 75. Both qPCR and flow cytometry show that these cells express GPR 75 but do not express CCR 5, CCR 3 or CCR 1 receptors. SY ‐ SY 5Y cells were then used to examine CCL 5‐mediated signaling. We report that CCL 5 promotes a time‐ and concentration‐dependent phosphorylation of protein kinase B ( AKT ), glycogen synthase kinase 3β, and extracellular signal–regulated kinase ( ERK ) 1/2. Specific antagonists of CCR 5, CCR 3, and CCR 1 did not prevent CCL 5 from increasing phosphorylated AKT or ERK . Moreover, CCL 5 promotes a time‐dependent internalization of GPR 75. Lastly, knocking down GPR 75 expression by a CRISPR ‐Cas9 approach inhibited the ability of CCL 5 to activate pERK in SH ‐ SY 5Y cells. Therefore, we propose that GPR 75 is a novel receptor for CCL 5 that could explain some of the pharmacological action of this chemokine. These findings may help in the development of small molecule GPR 75 agonists that mimic CCL 5. Open Practices This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/ . image