Zebrafish model of palmitic acid induced MAFLD recapitulates pathways conserved in mice and humans

Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD) is a major global health issue, affecting millions, yet its underlying molecular mechanisms remain poorly understood. Here, we propose a novel diet-induced zebrafish model to investigate pathophysiology of MAFLD. To validate the model, we performed comprehensive histological analysis and molecular assessments, including RNA-sequencing, to characterize the disease progression. These approaches enabled us to examine the molecular alterations underlying MAFLD and identify key genes and pathways involved in its development. Our results demonstrate that zebrafish subjected to a high-fat diet exhibit significant weight gain and show prominent fat accumulation in the liver, as confirmed by Oil Red O and BODIPY staining. Quantitative PCR analysis reveals upregulation of key lipogenic genes, including acc, fasn, hmgcs1, and hmgcra, indicating enhanced lipid synthesis. Immunoblotting also shows increased expression of several proteins (SIRT1, SREBP-1c, CEBPA and PGC-1α) involved in lipogenesis and glucose metabolism. Additionally, we observe increased expression of genes associated with endoplasmic reticulum stress, such as atf6, xbp1, gadd45a, and ddit3, along with activation of the mitochondrial unfolded protein response and inflammatory pathways, as indicated by elevated levels of hspd1, hspa9, clpp, lonp1, il1β and il8. These findings point to mitochondrial dysfunction, further supported by the dysregulation of genes involved in oxidative phosphorylation, including uqcrc2, cox4i1, sdha, nd1, and atp5f1b at both mRNA and protein levels. Transcriptomic profiling identifies new candidate markers such as inha, gck, ces2a, id3 and highlights dysregulated pathways involved in metabolism, insulin signaling, and cellular stress, offering insights into MAFLD progression. This study establishes a zebrafish model that recapitulates key features of MAFLD, including histopathological and metabolic alterations. Through transcriptomic and protein analysis, we identify novel biomarkers and pathways, providing new insights into MAFLD pathogenesis and highlighting potential therapeutic targets.