Rational Design of Small-Molecule Stabilizers of Human Fumarylacetoacetate Hydrolase for the Treatment of Tyrosinemia Type I

Hereditary tyrosinemia type 1 (HT1) stems from the loss of fumarylacetoacetate hydrolase (FAH) activity, causing severe liver-kidney disease. Nitisinone does not restore FAH function and carries metabolic and dietary burdens. Here, we used an integrated workflow guided by X-ray structures of human FAH to obtain small-molecule pharmacological chaperones that bind with low-μM affinity and stabilize FAH. Hits were validated by NMR and isothermal titration calorimetry. Protein stabilization was assessed by DOSY-NMR and circular dichroism; functional effects were tested in FAH activity assays, a CRISPR-engineered cellular model, and testing in an animal model of HT1. Compounds shifted the G337S pathological variant toward the active dimer and slowed unfolding/aggregation, resulting in dose-dependent enhancement of FAH activity and partial rescue of FAH homeostasis in cells and the liver tissue of a mouse model of HT1. These molecules support a therapeutic approach that could complement nitisinone in HT1.