Oxygen-dependent Regulation of Erythropoietin Receptor Turnover and Signaling.

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 factor α, 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 the β domain of VHL and polyubiquitylation via ECV, leading to increased EPOR turnover. In addition, several type-specific VHL disease-causing 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 secondbona fidehydroxylation-dependent substrate of VHL that potentially influences oxygen homeostasis and contributes to the complex genotype-phenotype correlation in VHL disease.