EPO does not promote interaction between the erythropoietin and beta-common receptors

A direct interaction between the erythropoietin (EPOR) and the beta-common (beta c) receptors to form an Innate Repair Receptor (IRR) is controversial. On one hand, studies have shown a functional link between EPOR and beta c receptor in tissue protection while others have shown no involvement of the beta c receptor in tissue repair. To date there is no biophysical evidence to confirm a direct association of the two receptors either in vitro or in vivo. We investigated the existence of an interaction between the extracellular regions of EPOR and the beta c receptor in silico and in vitro (either in the presence or absence of EPO or EPO-derived peptide ARA290). Although a possible interaction between EPOR and beta c was suggested by our computational and genomic studies, our in vitro biophysical analysis demonstrates that the extracellular regions of the two receptors do not specifically associate. We also explored the involvement of the beta c receptor gene (Csf2rb) under anaemic stress conditions and found no requirement for the beta c receptor in mice. In light of these studies, we conclude that the extracellular regions of the EPOR and the beta c receptor do not directly interact and that the IRR is not involved in anaemic stress.