Erythropoietin receptor and Innate Repair Receptor complex (EPOR/IRR)

The Erythropoietin receptor (EPOR) and its associated cytoprotective complex, often termed the Innate Repair Receptor (IRR), represent a dual-function signaling system critical for both hematopoiesis and tissue homeostasis [1][2]. The classical EPOR homodimer is primarily expressed on erythroid progenitor cells, where its activation by erythropoietin (EPO) triggers the JAK2/STAT5 pathway to drive red blood cell production [3][5]. In contrast, the cytoprotective IRR is a heteromeric complex composed of EPOR and the cytokine receptor common subunit beta (CD131/CSF2RB), which is upregulated in non-hematopoietic tissues following injury or metabolic stress [2][4]. Activation of the IRR initiates tissue-protective signaling cascades, such as the PI3K/Akt and MAPK pathways, which inhibit apoptosis, reduce inflammation, and promote functional recovery in organs like the brain, heart, and kidneys [1][6]. While traditional erythropoiesis-stimulating agents (ESAs) target both receptor types, they are primarily utilized for treating anemia, though their use is limited by risks of hypertension and thrombosis [5]. Modern drug development has focused on selective IRR agonists, such as cibinetide, which aim to provide the benefits of tissue repair without the adverse effects associated with increased red blood cell mass [4][6].

Other names

EPORInnate Repair ReceptorIRRTissue-Protective ReceptorTPREPOR-CD131 complexEPOR-CSF2RB complexErythropoietin receptor-cytokine receptor common subunit beta heteromer

Drugs targeting these receptors act as agonists. Erythropoiesis-stimulating agents (ESAs) bind the EPOR homodimer to trigger JAK2/STAT5 signaling, promoting red blood cell survival and proliferation [3][5]. Selective Innate Repair Receptor (IRR) agonists bind the EPOR/CD131 heterocomplex to activate PI3K/Akt, MAPK, and NF-κB pathways, which mediate anti-apoptotic and anti-inflammatory responses in non-hematopoietic tissues [1][4].