PT  - JOURNAL ARTICLE
AU  - James L. Miller
AU  - Timothy J. Church
AU  - Dmitri Leonoudakis
AU  - Karen Lariosa-Willingham
AU  - Normand L. Frigon
AU  - Connie S, Tettenborn
AU  - Jeffrey R. Spencer
AU  - Juha Punnonen
TI  - Discovery and Characterization of Nonpeptidyl Agonists of The Tissue-Protective Erythropoietin Receptor
AID  - 10.1124/mol.115.098400
DP  - 2015 Jan 01
TA  - Molecular Pharmacology
PG  - mol.115.098400
4099  - http://molpharm.aspetjournals.org/content/early/2015/05/27/mol.115.098400.short
4100  - http://molpharm.aspetjournals.org/content/early/2015/05/27/mol.115.098400.full
AB  - Erythropoietin (EPO) and its receptor are expressed in a wide variety of tissues, including the central nervous system. Local expression of both EPO and its receptor is upregulated upon injury or stress and plays a role in tissue homeostasis and cytoprotection. High-dose systemic administration or local injection of recombinant human EPO has demonstrated encouraging results in several models of tissue protection and organ injury, while poor tissue availability of the protein limits its efficacy. Here, we describe the discovery and characterization of the nonpeptidyl compound STS-E412, which selectively activates the tissue-protective EPO receptor, comprising an EPO receptor subunit (EPOR) and the common beta-chain (CD131). STS-E412 triggered EPO receptor phosphorylation in human neuronal cells. STS-E412 also increased phosphorylation of EPOR, CD131 and the EPO-associated signaling molecules JAK2 and AKT in HEK-293 transfectants expressing EPOR and CD131. At low nanomolar concentrations, STS-E412 provided EPO-like cytoprotective effects in primary neuronal cells and renal proximal tubular epithelial cells. The receptor selectivity of STS-E412 was confirmed by a lack of phosphorylation of the EPOR/EPOR homodimer, lack of activity in off-target selectivity screening, and lack of functional effects in erythroleukemia cell line TF-1 and CD34+ progenitor cells. The low molecular weight, permeability through artificial membranes and Caco-2 cell monolayers, and low polar surface area of STS-E412 suggest a potential for oral bioavailability and blood-brain barrier penetrance. To our knowledge, STS-E412 is the first selective activator of the tissue-protective EPOR/CD131 receptor. Further evaluation of the potential of STS-E412 in CNS diseases and organ protection is warranted.