International Union of Basic and Clinical Pharmacology : CXVIII. Update on the nomenclature for atypical chemokine receptors, including ACKR5

Abstract

Chemokines signal through classical G protein–coupled receptors to induce cell migration during development, immune homeostasis, and multiple diseases. Over the last decade, a subfamily of atypical chemokine receptors (ACKRs) was delineated from G protein–coupled receptors based on their inability to trigger conventional G protein signaling or mediate cell migration in response to chemokines. These receptors nevertheless play an important role within the chemokine system by sequestering, transporting, or internalizing chemokines, thereby regulating their availability and shaping their gradients. GPR182, the recently deorphanized chemokine receptor, shares about 30% of sequence similarity with its closest relative ACKR3. GPR182 is mainly expressed on endothelial cells and was proposed to act as a scavenger regulating the availability of a large set of chemokines from the CXC, CC, and XC families and to act cooperatively with ACKR3 and ACKR4. Unlike other ACKRs, GPR182 was shown to have a strong constitutive interaction with β-arrestins that is required for intracellular receptor trafficking and chemokine scavenging. Chemokine ligation of GPR182 has no additional detectable impact on β-arrestin recruitment. Genetic ablation of GPR182 affects spleen size, myelopoiesis, and serum chemokine levels, indicating its role in chemokine homeostasis and immune regulation. GPR182 was also reported to regulate immune responses to bloodborne antigens and tumorigenesis. Taken together, compelling cumulative evidence indicates that GPR182 does not trigger G protein-mediated signaling but acts as a scavenger for chemokines in vitro and in vivo, strongly supporting its inclusion as ACKR5 in the systematic nomenclature of chemokine receptors.