The partial erythropoietin receptor agonist ML1-R is a potent neuroprotective drug with a distinct signaling profile.

Erythropoietin (EPO) is a glycoprotein that stimulates red blood cell production in the bone marrow and protects neurons from oxidative stress, making it a potential treatment for various neurological diseases. However, EPO analogs often lead to side effects like excessive erythropoiesis and tumor growth. In this study, we aimed to develop ML1-R, a peptide derived from the C-helix of EPO, to enhance neuroprotection while minimizing adverse effects. By modifying amino acids that interact with EPO receptors (EPORs), ML1-R activated EPORs differently from recombinant EPO (reEPO). ML1-R provided stronger neuroprotection than reEPO without promoting cell proliferation. In a murine stroke models and in-vitro neuron cultures, ML1-R reduced brain injury and prevented neuronal death caused by glutamate-induced excitotoxicity and hypoxia-reoxygenation. AlphaFold3 computational analysis showed distinct binding affinity and geometric structures between ML1-R–EPOR and EPO–EPOR complexes. ML1-R prolonged JAK2 activation and activated Akt/Erk signaling in distinct patterns, increasing EPORs on cell surface membranes. This reduced apoptosis and alleviated calcium overload, reactive oxygen species generation, and mitochondrial dysfunction induced by glutamate-induced excitotoxicity and hypoxia–reoxygenation. In conclusion, these findings highlight ML1-R as a promising candidate to treat ischemic stroke, reperfusion brain injury, and neurodegenerative diseases.