Urolithin A attenuates auditory cell senescence by activating mitophagy

Abstract Aging of sensory organs is associated with a decline in mitochondrial function and the accumulation of dysfunctional mitochondria. Impaired mitophagy blocks the turnover of dysfunctional mitochondria and leads to their accumulation. Urolithin A (UA) induces mitophagy in various mammalian cells. This study was aimed at investigating the effect of the mitophagy activator, UA, on premature senescent auditory cells. The levels of cellular senescence(definition)-associated p53 and p21 significantly increased in H 2 O 2 -induced senescent House Ear Institute‐Organ of Corti 1 (HEI-OC1) cells and cochlear explants. However, the levels of mitophagy-related molecules significantly decreased. UA significantly decreased the expression of senescence-associated p53 and p21, and increased the expression of mitophagy-related proteins, in H 2 O 2 -induced senescent cells and cochlear explants. The percentage of β-galactosidase-stained senescent cells also reduced in H 2 O 2 -treated cells and cochlear explants upon UA pre-treatment. The formation of mitophagosomes and mitophagolysosomes was restored upon UA pre-treatment of H 2 O 2 -induced senescent cells. The knockdown of mitophagy-related genes ( Parkin and Bnip3 ) resulted in annulment of UA-induced anti-senescent activity. UA significantly increased the ATP content, mitochondrial DNA (mtDNA) integrity, and mitochondrial membrane potential in senescent HEI-OC1 cells. These findings indicate that UA counteracted mitophagy decline and prevented premature senescence in auditory cells. Hence, UA administration might be a promising strategy for preventing mitochondrial dysfunction(definition) in patients with age-related hearing loss.