Iron regulates lipid droplet formation in hepatocytes via heme oxygenase-1 mediated ferroptosis

Background

Iron overload has been implicated in the disruption of hepatic lipid metabolism, potentially contributing to non-alcoholic fatty liver disease and other hepatic disorders. However, the underlying mechanisms connecting iron overload to lipid metabolism dysregulation remain elusive. This study aimed to investigate the effect of iron overload on lipid droplet formation, and to explore the regulatory mechanism of iron overload on lipid metabolism through the lens of ferroptosis.

Methods

Iron overload and ferroptosis models were established by treating AML12 mouse hepatocytes with ferric ammonium citrate (FAC) or erastin, a classical ferroptosis inducer, respectively. Lipid droplet formation, mitochondria morphology, and lipid peroxidation index were detected.

Results

Perilipin 2 (PLIN2), a lipid droplet-specific marker, exhibited a 1.2-fold increase (p < 0.01) at 50 μM FAC, but decreased by 23 % (p < 0.05) at higher concentrations (250 μM or 500 μM). Similarly, in erastin-induced ferroptosis hepatocytes, PLIN2 expression progressively declined with increasing erastin concentrations, showing a 29 % reduction (p < 0.05) at 30 μM, accompanied by a reduction in both the size and number of lipid droplets. Notably, both FAC and erastin treatments resulted in an initial increase in lipid droplet levels at low concentrations, followed by a decrease at higher concentrations. Additionally, both iron overload and ferroptosis significantly upregulated heme oxygenase-1 (HO-1) expression, whose overexpression exacerbated ferroptosis and diminished lipid storage.

Conclusion

Our findings showed that iron overload perturbs hepatocyte lipid metabolism, with ferroptosis playing a pivotal role in lipid regulation through HO-1-mediated mechanisms.