Lipid overload triggers PERK-ALCAT1-mediated mitophagy failure in hepatocytes.

Mitochondria-associated endoplasmic reticulum membranes (MAMs), contact sites between the endoplasmic reticulum (ER) and mitochondria, are critical for calcium signaling and lipid metabolism. However, how MAMs contribute to mitochondrial dysfunction in lipid overload-induced fatty liver remains unclear. Here, using teleost fish as a model, we showed that high-fat diets promoted the aggregation of PERK and ALCAT1 at MAMs, causing mitochondrial calcium overload and membrane depolarization, and impairing PINK1/Parkin-dependent mitophagy. Acetylation of PERK at lysine 388 facilitated its binding to ALCAT1, while activation of SIRT1 by resveratrol induced site-specific deacetylation of PERK, disrupted PERK-ALCAT1 interaction, and restored mitophagy and mitochondrial integrity. These findings revealed a conserved SIRT1-PERK-ALCAT1 signaling axis linking ER stress to mitophagy failure and identified a potential nutritional intervention to alleviate lipid-induced hepatic injury. This mechanism is conserved across species and offers a basis for controlling metabolic dysfunction-associated steatotic liver disease (MASLD) in teleosts and potentially other vertebrate systems.