Mitophagy as a guardian against cellular aging.

Mitophagy, the selective autophagic clearance of damaged mitochondria, is considered vital for maintaining mitochondrial quality and cellular homeostasis; however, its molecular mechanisms, particularly under basal conditions, and its role in cellular physiology remain poorly characterized. We recently demonstrated that basal mitophagy is a key feature of primary human cells and is downregulated by immortalization, suggesting its dependence on the primary cell state. Mechanistically, we demonstrated that the PINK1-PRKN-SQSTM1 pathway regulates basal mitophagy, with SQSTM1 sensing superoxide-enriched mitochondria through its redox-sensitive cysteine residues, which mediate SQSTM1 oligomerization and mitophagy activation. We developed STOCK1N-57534, a small molecule that targets and promotes this SQSTM1 activation mechanism. Treatment with STOCK1N-57534 reactivates mitophagy downregulated in senescent and naturally aged donor-derived primary cells, improving cellular senescence(-like) phenotypes. Our findings highlight that basal mitophagy is protective against cellular senescence and aging, positioning its pharmacological reactivation as a promising anti-aging strategy. IR: ionizing radiation; ROS: reactive oxygen species; SARs: selective autophagy receptors.