A Small‐Molecule Inhibitor of Factor Inhibiting HIF Binding to a Tyrosine‐flip Pocket for the Treatment of Obesity

In animals limiting oxygen upregulates hypoxia‐inducible factor (HIF) promoting a metabolic shift towards glycolysis. Factor inhibiting HIF (FIH) is an asparaginyl hydroxylase that regulates HIF function by reducing its interaction with histone acetyl transferases. HIF levels are negatively regulated by the HIF prolyl hydroxylases (PHDs), which like FIH, are 2‐oxoglutarate(2OG) oxygenases. Genetic loss of FIH promotes both glycolysis and aerobic metabolism. FIH has multiple non‐HIF substrates making it challenging to connect its biochemistry with physiology. A structure‐mechanism guided approach identified a highly potent in vivo active FIH inhibitor, ZG‐2291, binding of which promotes a conformational flip of a catalytically important tyrosine, enabling selective inhibition of FIH over other JmjC subfamily 2OG oxygenases. Consistent with genetic studies, ZG‐2291 promotes thermogenesis and ameliorates symptoms of obesity and metabolic dysfunction in ob/ob mice. The results reveal ZG‐2291 as a useful probe for the physiological functions of FIH and identify FIH inhibition as a promising strategy for obesity treatment.