Hrd1-mediated ACLY ubiquitination alleviate NAFLD in db/db mice

• Published in: Metabolism, clinical and experimental clinical and experimental, 2021-01, Vol.114, p.154349-154349, Article 154349
• Main Authors: Li, Kai, Zhang, Kaini, Wang, Hai, Wu, Yangyang, Chen, Nuoqi, Chen, Jinfeng, Qiu, Chen, Cai, Pengpeng, Li, Min, Liang, Xiubin, Su, Dongming
• Format: Article
• Language: English
• Subjects: Acly stability; Animals; ATP Citrate (pro-S)-Lyase - metabolism; Hep G2 Cells; Hepatocytes - metabolism; Hrd1; Humans; Insulin resistance; Insulin Resistance - physiology; Lipogenesis - physiology; Liver - metabolism; Liver steatosis; Mice; Non-alcoholic Fatty Liver Disease - metabolism; Obesity - metabolism; Tandem Mass Spectrometry; Ubiquitin-Protein Ligases - metabolism; Ubiquitination; Ubiquitination - physiology
• ISSN: 0026-0495; 1532-8600
• DOI: 10.1016/j.metabol.2020.154349

The functions of Acly in regulating nonalcoholic fatty liver disease (NAFLD) have been identified; however, the dynamic control of Acly expression under the pathological state of metabolic disorders has not been fully elucidated. Previous studies reported an ubiquitin-proteasome–mediated degradation of Acly, but the mechanism is still largely unknown. Co-IP–based mass spectrum (MS/MS) assays were performed in HepG2 and Hepa1-6 hepatocytes and mouse liver tissue. The protein-protein interaction and ubiquitin modification of Hrd1 on Acly were confirmed by co-IP based immuno-blotting. Acetyl-CoA levels and lipogenesis rates were determined. The roles of Hrd1 on NAFLD and insulin resistance were tested by adenovirus-mediated overexpression in db/db mice or in separated primary hepatocytes. Hrd1, a subunit of the endoplasmic reticulum-associated degradation (ERAD) complex, interacted with and ubiquitinated Acly, thereby reducing its protein level. Hrd1 suppressed the acetyl-CoA level and inhibited lipogenesis through an Acly-dependent pathway. The expression of hepatic Hrd1 was negatively associated with NAFLD, whereas overexpression of Hrd1 ameliorated hepatic steatosis and enhanced insulin sensitivity, both in db/db mice and in separated mouse primary hepatocytes. Our results suggest that Acly, a master enzyme that regulates lipogenesis, is degraded by Hrd1 through ubiquitin modification. The activation of Hrd1 in hepatocytes might therefore represent a strategic approach for NAFLD therapy. [Display omitted] •Hrd1 ubiquitinates and degrades Acly, a key enzyme of de novo lipogenesis.•Hrd1 suppress lipogenesis and reduce Acetyl-CoA through downregulation of Acly.•Expression level of Hrd1 is negatively associated with liver steatosis.•Forced expression of Hrd1 reversed fatty liver and insulin resistance in db/db mice.