PDCD4-driven steatosis via the HNF4A/GK axis is attenuated by the natural compound isosinensetin.

BACKGROUND: Programmed cell death factor 4 (PDCD4) has been implicated in various metabolic disorders. However, its role and underlying mechanisms in metabolic dysfunction-associated steatotic liver disease (MASLD) have not been fully elucidated. PURPOSE: This study aimed to define the role of PDCD4 in hepatic steatosis and identify potential therapeutic strategies targeting its downstream metabolic pathway. METHODS: RNA sequencing was performed on liver tissues from wild-type and PDCD4-knockout mice to identify dysregulated metabolic pathways and candidate downstream genes. The PDCD4-HNF4A-GK regulatory pathway was investigated using genetic, histological, biochemical, and molecular analyses in mouse models and hepatocytes. Virtual screening and molecular docking were used to identify candidate GK-targeting compounds. RESULTS: Hepatocyte-specific PDCD4 deletion increased hepatic GK expression and aggravated lipid accumulation. GK knockout markedly attenuated PDCD4 deficiency-induced lipid accumulation in hepatocytes. Mechanistically, PDCD4 suppressed HNF4A translation, thereby limiting HNF4A-dependent GK transcription. Virtual screening identified isosinensetin as a candidate GK inhibitor. Isosinensetin inhibited GK activity and reduced lipid accumulation in hepatocytes and CDAHFD-fed mice. CONCLUSIONS: These results suggest that GK may warrant further investigation for ameliorating hepatic steatosis, and provide preliminary evidence for the PDCD4-HNF4A-GK axis in the regulation of hepatic triglyceride metabolism. Further studies are required to establish the relevance of this axis to the full spectrum of MASLD pathology.