Widespread expression of erythropoietin receptor in brain and its induction by injury

Abstract

Erythropoietin (EPO) exerts potent neuroprotective, neuroregenerative and procognitive functions. However, unequivocal demonstrationof erythropoietin receptor (EPOR) expression in brain cells has remained difficult since previously available anti-EPORantibodies (EPOR-AB) were unspecific. We report here a new, highly specific, polyclonal rabbit EPOR-AB directed against differentepitopes in the cytoplasmic tail of human and murine EPOR and its characterization by mass spectrometric analysis of immunoprecipitatedendogenous EPOR, Western blotting, immunostaining and flow cytometry. Among others, we applied genetic strategiesincluding overexpression, Lentivirus-mediated conditional knockout of EpoR and tagged proteins, both on cultured cellsand tissue sections, as well as intracortical implantation of EPOR-transduced cells to verify specificity. We show examples of EPORexpression in neurons, oligodendroglia, astrocytes and microglia. Employing this new EPOR-AB with double-labeling strategies, wedemonstrate membrane expression of EPOR as well as its localization in intracellular compartments such as the Golgi apparatus.Moreover, we show injury-induced expression of EPOR. In mice, a stereotactically applied stab wound to the motor cortex leadsto distinct EpoR expression by reactive GFAP-expressing cells in the lesion vicinity. In a patient suffering from epilepsy, neurons andoligodendrocytes of the hippocampus strongly express EPOR. To conclude, this new analytical tool will allow neuroscientists to pinpointEPOR expression in cells of the nervous system and to better understand its role in healthy conditions, including brain development,as well as under pathological circumstances, such as upregulation upon distress and injury.