Production of functional recombinant prolyl hydroxylase-2 enzyme in insect cells for small molecule inhibitor screening studies.

Prolyl hydroxylase-2 (PHD2) is a dioxygenase enzyme that specifically hydroxylates the hypoxia inducible factor (HIF) which then targets it for degradation in oxygenated cells. Inhibition of the activity of the PHD2 enzyme under hypoxic environmental conditions acts to upregulate HIF. Thus, PHD2 inhibitors may serve as a promising treatment for HIF-dependent diseases. In this study, recombinant PHD2 protein was successfully expressed using a baculovirus-insect cell expression secretory system. PHD2 was purified and in combination with bacterially expressed functional von Hippel Lindau protein-elongin B-elongin C (VBC) protein complex was used to successfully develop a fluorescence-based PHD2 activity assay. Myricetin was identified as a novel potent PHD2 inhibitor by high-throughput screening of a natural compound library. Further studies showed that treatment of human neuroblastoma SH-SY5Y cells with Myricetin increased HIF-1α protein levels. These results indicate that the insect cell expression system is capable of producing highly active recombinant PHD2 protein from which a fluorescence-based activity assay can be developed for high-throughput screening applications.