Oxygen-dependent regulation of erythropoietin receptor turnover and signaling

Abstract

von Hippel-Lindau (VHL) disease is a rare familial cancer predisposition syndrome caused by a loss or mutation in a single gene, VHL, but it exhibits a wide phenotypic variability that can be categorized into distinct subtypes. The phenotypic variability has been largely argued to be attributable to the extent of deregulation of the α subunit of hypoxia-inducible factorα, a well established target of VHL E3 ubiquitin ligase, ECV (Elongins/ Cul2/VHL). Here, we show that erythropoietin receptor (EPOR) is hydroxylated on proline 419 and 426 via prolyl hydroxylase 3. EPOR hydroxylation is required for binding to theβ domain of VHL and polyubiquitylation via ECV, leading to increased EPOR turnover. In addition, several type-specific VHL diseasecausing mutants, including those that have retained proper binding and regulation of hypoxia-inducible factor α, showed a severe defect in binding prolyl hydroxylated EPOR peptides. These results identify EPOR as the second bona fide hydroxylation- dependent substrate of VHL that potentially influences oxygen homeostasis and contributes to the complex genotypephenotype correlation in VHL disease.