Hepatic NMNAT1 is required to defend against alcohol-associated fatty liver disease

Nicotinamide mononucleotide adenylyltransferase 1 (NMNAT1), a nicotinamide adenine dinucleotide (NAD⁺) synthetase in Preiss-Handler and salvage pathways, governs nuclear NAD⁺ homeostasis. This study investigated the role of NMNAT1 in alcohol-associated liver disease (ALD). Decreased NMNAT1 expression and activity were observed in the liver of patients with alcohol-associated hepatitis and either liver or primary hepatocytes from ALD mice. F-box and WD repeat domain containing 7 (FBXW7)-regulated interferon regulatory factor 1 (IRF1) ubiquitination degradation contributed to the alcohol-inhibited NMNAT1 transcriptional level. Hepatic NMNAT1 knockout aggravated alcohol-induced hepatic NAD⁺ decline and further hepatic steatosis and liver injury. Metabolomics and transcriptomics interaction revealed that the cysteine sulfinic acid decarboxylase (CSAD)-regulated taurine pathway was involved in NMNAT1-disrupted hepatic lipid metabolism in ALD. Hepatic CSAD overexpression or taurine supply attenuated hepatic NMNAT1 knockout-aggravated ALD. Hepatic NMNAT1 loss inhibited NMN-protected ALD. Replenishing hepatic NMNAT1 reversed liver lipid accumulation in ALD mice. These findings identified NMNAT1 as a promising therapeutic target for ALD.