Abstract
Objectives:
Age-related hearing disorder is known to be elicited by mitochondrial dysfunction caused by various stresses including reactive oxygen species. Recent studies have found that autophagy plays an important role in maintenance of cellular function sequestering damaged, oxidized or dysfunctional intracellular components and organelles, and is also associated with aging. However, the role of autophagy on senescence of inner ear and age-related hearing loss remains unclear. In this study, we investigated the molecular mechanism of autophagy and senescence in auditory cells.
Methods:
We used auditory cell line HEI-OC1. After treatment with H2O2, cell viability and population doubling time were counted. We detected autophagy related proteins with western blotting. SA-b-gal staining was performed for detecting cellular senescence. Atg7 and AMPKa siRNA were transfected into HEI-OC1 cells with electrophoration.
Results:
The cell viability of H2O2-treated HEI-OC1 was decreased in a time- and dose-dependent manner. While senescent cells are characterized by its ceased proliferation, the cell doubling time was delayed in H2O2-treated HEI-OC1. The activity of SA-b-gal was increased in H2O2-treated HEI-OC1 cells. The expression of LC3-II, a monitoring marker of autophagy, was induced after treatment with H2O2. The protein level of p-AMPK, known as a key gene of life span elongation, also was increased in H2O2-treated HEI-OC1. The premature senescence was significantly induced in AMPK and Atg7 KD HEI-OC1, compared with control cells.
Conclusions:
Our results suggested that autophagy and AMPK activation play a crucial role of cellular senescence in auditory cell under oxidative stress.
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