Elevated Porcupine Disrupts Lipid Metabolism and Promotes Inflammatory Response in MASLD

Background and aims: Metabolic dysfunction-associated steatotic liver disease (MASLD) presents a high incidence globally and is a major cause of cirrhosis and hepatocellular carcinoma, lacking of efficient interventions. Patients with MASLD exhibit exceeded serum levels of palmitic acid (PA). However, the association between PA and MASLD remains obscure.

Methods: Gene expression omnibus dataset analysis, western blotting, mRNA-sequencing, RT-qPCR, a click chemistry-immunoprecipitation-immunofluorescence system, ELISA, lipid extraction and UHPLC-MS/MS analysis, CyTOF mass cytometry, gene knockdown via lentivirus-mediated shRNA, and high-fat methionine and choline-deficient diet-fed WT and db/db mice models were used to reveal the expression and functions of Porcupine in MASLD development both in vitro and in vivo.

Results: Our findings show that PA, as a crucial substrate for protein palmitoylation, induced the expression of palmitoyltransferase Porcupine in a time-dependent manner. This induction was closely associated with dysregulated lipid metabolism and stimulated inflammatory response observed in vitro. Porcupine protein levels were significantly increased in liver tissues from both MASLD mice models, which was predominantly localised in lipid droplet-rich hepatocytes. Pharmacological inhibition of Porcupine by Wnt974 markedly ameliorated the aberrant lipid accumulation and inflammatory response in mouse livers. Furthermore, increased Porcupine positively correlated with CD36 at protein levels, and its inhibition or knockdown decreased CD36 protein levels via mechanisms irrelevant to transcriptional regulation, but primarily dependent on protein palmitoylation.

Conclusions: The current study reveals that PA-induced Porcupine disrupts lipid metabolism and promotes inflammatory response during MASLD development, which can be ameliorated by the Porcupine inhibitor Wnt974. Therefore, Porcupine may be a potential pharmacological target for the treatment of MASLD.