HIF-1α peptide derivatives with modifications at the hydroxyproline residue as activators of HIF-1α

Peptides containing 556–575 residues of HIF-1α with modifications at the Pro-564 residue were synthesized and assayed against the interaction between hydroxylated HIF-1α and VBC. Two inhibitors showing highest potency were also found to induce HIF stabilization when transfected in HeLa cells. Hypoxia-inducible factor (HIF)-1α undergoes degradation under normoxia, which involves its proline hydroxylation and subsequent binding of proline-hydroxylated HIF-1α to the von Hippel-Lindau protein–Elongin B–Elongin C (VBC) complex. In this study, we designed and synthesized a series of peptides containing 556–575 residues of HIF-1α with modifications at the Pro-564 residue to inhibit the interaction between proline-hydroxylated HIF-1α and VBC. Employing a fluorescence polarization-based interaction assay, we evaluated inhibitory potency of these peptides and selected potent inhibitors. We then analyzed their effects in the cell level to show that the selected inhibitors induced HIF-1α stabilization in normoxic cells. Considering that proline hydroxylation of HIF-1α is routinely targeted for modulating the HIF pathway, our approach of using inhibitors against the interactions between HIF-1α and VBC would provide an alternative way of upregulating HIF-1 activity.