DHCR7 as a novel regulator of ferroptosis in hepatocytes

Recent evidence indicates that ferroptosis is implicated in the pathophysiology of various liver diseases; however, the mechanism of ferroptosis regulation in the liver is poorly understood. Here, using the whole-genome screening approach, we identified 7-dehydrocholesterol reductase (DHCR7), the terminal enzyme of cholesterol biosynthesis, as a novel regulator of ferroptosis in hepatocytes. Genetic and pharmacological inhibition (with AY9944) of DHCR7 suppressed lipid peroxidation and ferroptosis in human hepatocellular carcinoma Huh-7 cells. DHCR7 inhibition increased its substrate, 7-dehydrocholesterol (7-DHC), and extrinsic 7-DHC supplementation in turn suppressed ferroptosis. On the other hand, cholesterol deprivation had no effect on ferroptosis. A 7-DHC-derived oxysterol metabolite, 3β,5α-dihydroxycholest-7-en-6-one (DHCEO), was increased by a ferroptosis inducer RSL-3 in DHCR7-deficient cells, suggesting that the ferroptosis-suppressive effect of DHCR7 inhibition was driven by intracellular 7-DHC as a radical scavenger. While extrinsic 7-DHC supplementation suppressed ferroptosis in various cancer cells, pharmacological DHCR7 inhibition by AY9944 showed cell-type specific effects, which could be explained by high DHCR7 expression in Huh-7 cells. We further showed that AY9944 suppressed ferroptosis in murine primary hepatocytes in vitro and systemic administration of AY9944 inhibited hepatic ischemia-reperfusion injury in vivo . These findings provide new insights into the regulatory mechanism of liver ferroptosis and suggest that DHCR7 inhibition is a potential therapeutic option for ferroptosis-related liver diseases. ### Competing Interest Statement The authors have declared no competing interest. * ALD : alcoholic liver disease ALT : alanine aminotransferase AST : aspartic aminotransferase 7-DHC : 7-dehydrocholesterol DHCEO : 3β,5α-dihydroxycholest-7-en-6-one DHCR7 : 7-dehydrocholesterol reductase Fer-1 : Ferrostatin-1 GFP : green fluorescent protein GPX4 : glutathione peroxidase 4 GSH : glutathione HE : hematoxylin and eosin IRI : ischemiareperfusion injury LA : linoleic acid LC-MS/MS : liquid chromatograph-mass spectrometry Mβ-CD : Methyl-β-cyclodextrin NASH : non-alcoholic steatohepatitis NGS : next-generation sequencer PUFAs : polyunsaturated fatty acids