Prolyl hydroxylase domain-containing protein (PHD)

Prolyl hydroxylase domain-containing proteins (PHDs), also referred to as HIF-prolyl hydroxylases, are iron- and 2-oxoglutarate-dependent dioxygenase enzymes that serve as cellular oxygen sensors. They catalyze the hydroxylation of specific proline residues in the hypoxia-inducible factor alpha (HIF-α) subunit in an oxygen-dependent manner, targeting HIF-α for proteasomal degradation via recognition by the Von Hippel–Lindau (VHL) E3 ligase. Under hypoxic conditions, PHD activity is inhibited, resulting in HIF-α stabilization, dimerization with HIF-1β, and activation of transcriptional responses crucial for cellular adaptation to low oxygen. These enzymes play a fundamental physiological role in oxygen homeostasis and are implicated as therapeutic targets in anemia, cancer, ischemia, and inflammatory diseases. Pharmacological inhibition of PHDs leads to upregulation of HIF target genes, which stimulates erythropoiesis and angiogenesis, forming the mechanistic basis for several drugs approved or in development for the treatment of anemia associated with chronic kidney disease and other disorders[1][2][3][4][6][8].

Other names

HIF-prolyl hydroxylasehypoxia-inducible factor prolyl hydroxylaseprolyl hydroxylase domain proteinoxygen sensorPHD enzymeEGLN

Inhibition of prolyl hydroxylase domain-containing protein prevents hydroxylation of HIF-α, leading to its stabilization, accumulation, and transcriptional activation of hypoxia-responsive genes Mimics cellular hypoxic response under normoxia