AUF1 Restrains Hepatocyte Senescence by Maintaining Mitochondrial Homeostasis in AML12 Hepatocyte Model

Cellular senescence, a hallmark of aging, involves irreversible growth arrest and an enhanced senescence-associated secretory phenotype (SASP). It is often accompanied by mitochondrial dysfunction and altered inter-organelle communication. Using a chronic oxidative stress model in AML12 hepatocytes, we confirmed senescence by canonical assays (e.g., SA β-gal positivity and proliferation arrest) and observed a decline in the RNA-binding protein AUF1 (hnRNP D). AUF1 knockdown further amplified senescent phenotypes, including elongation of mitochondrial network, loss of mitochondrial membrane potential, reduced ATP level, and elevated mitochondrial reactive oxygen species (ROS). In addition, AUF1 knockdown weakened mitochondria-endoplasmic reticulum coupling and reduced mitochondrial Ca²⁺ load. At the molecular level, AUF1 binds to the 3' untranslated regions (3'UTRs) of Opa1 and Mfn2 and limits their abundance, thereby coupling post-transcriptional control to mitochondrial dynamics. In gain-of-function experiments, ectopic expression of AUF1 attenuated Opa1/Mfn2 induction, restored mitochondrial network architecture, and preserved bioenergetic function under pro-senescent stimuli. Collectively, these findings support a model in which AUF1 preserves mitochondrial homeostasis and thereby restrains the mitochondria-senescence axis in hepatocytes.