G protein–coupled receptor 21 in macrophages: An in vitro study

Authors

Valentina Bordano, University of Turin
Gemma K. Kinsella, Technological University DublinFollow
Stefania Cannito, University of Turin
Chiara Dianzani, University of Turin
Casimiro Luca Gigliotti, University of Eastern Piedmont
John C. Stephens, National University of Ireland, Maynooth
Chiara Monge, University of Turin
Claudia Bocca, University of Turin
Arianna C. Rosa, University of Turin
Gianluca Miglio, University of Turin
Umberto Dianzani, University of Eastern Piedmont
John B.C. Findlay, National University of Ireland, Maynooth
Elisa Benetti, University of TurinFollow

Document Type

Article

Rights

Available under a Creative Commons Attribution Non-Commercial Share Alike 4.0 International Licence

Disciplines

Biochemistry and molecular biology

Publication Details

Preprint.

Abstract

GPR21 is an orphan and constitutively active receptor belonging to the superfamily of G-Protein Coupled Receptors (GPCRs). GPR21 couples to the Gq family of G proteins and is markedly expressed in macrophages. Studies of GPR21 knock-out mice indicated that GPR21 may be involved in promoting macrophage migration. The aim of this study was to evaluate the role of GPR21 in human macrophages, analyzing (i) its involvement in cell migration and cytokine release and (ii) the consequence of its pharmacological inhibition by using the inverse agonist GRA2. THP-1 cells were activated and differentiated into either M1 or M2 macrophages. GPR21 expression was evaluated at gene and protein level, the signalling pathway was investigated by an IP1 assay, and cytokine release by ELISA. Cell migration was detected by the Boyden chamber migration assay, performed on macrophages derived from both the THP-1 cell line and human peripheral blood monocytes. In addition, we compared the effect of the pharmacological inhibition of GPR21 with the effect of the treatment with a specific GPR21 siRNA to downregulate the receptor expression, thus confirming that GRA2 acts as an inverse agonist of GPR21. GRA2 does not affect cell viability at the tested concentrations, but significantly reduces the release of TNF-α and IL-1β from M1 macrophages. The analysis of the migratory ability highlighted opposite effects of GRA2 on M1 and M2 macrophages since it decreased M1, while it promoted M2 cell migration. Therefore, the pharmacological inhibition of GPR21 could be of interest for pathological conditions characterized by low grade chronic inflammation.

DOI

https://doi.org/10.1016/j.ejphar.2022.175018

Recommended Citation

Valentina Bordano, Gemma K. Kinsella, Stefania Cannito, Chiara Dianzani, Casimiro Luca Gigliotti, John C. Stephens, Chiara Monge, Claudia Bocca, Arianna C. Rosa, Gianluca Miglio, Umberto Dianzani, John B.C. Findlay, Elisa Benetti, G protein–coupled receptor 21 in macrophages: An in vitro study, European Journal of Pharmacology, 2022, 175018, ISSN 0014-2999, DOI: 10.1016/j.ejphar.2022.175018.