miR-130b-3p involved in the pathogenesis of age-related hearing loss via targeting PPARγ and autophagy.

The study focuses on the underlying regulatory mechanism of age-related hearing loss (ARHL), which results from autophagy dysregulation mediated by miR-130b-3p targeting PPARγ. We constructed miR-130b-3p knockout (antagomir) and PPARγ over-expression (OE-PPARγ) mice model by injecting mmu-miR-130b-3p antagomir and HBAAV2/Anc80-m-Pparg-T2A-mCHerry into the right ear' round window of each mouse, respectively. In vitro, we introduced oxidative stress within HEI-OC1 cells by H2O2 and exogenously changed the miR-130b-3p and PPARγ levels. MiRNA level was detected by RT-qPCR, proteins by western blotting and immunohistochemistry. Morphology of autophagosomes was observed by electron microscopy. In vivo, the cochlea of aged mice showed higher miR-130b-3p expression and lower PPARγ expression, while exogenous inhibition of miR-130b-3p up-regulated PPARγ expression. Autophagy-related biomarkers expression (ATG5, Beclin-1 and LC3B II/I) decreased in aged mice, which reversely increased after the inhibition of miR-130b-3p. The elevation of PPARγ demonstrated similar effects. Contrarily, exogenous overexpression of miR-130b-3p resulted in the decrease of ATG5, Beclin-1 and LC3B II/I. We created oxidative stress within HEI-OC1 by H2O2, subsequently observed the formation of autophagosomes under electron microscope, so as the elevated cell apoptosis rate and weakened cell viability. MiR-130b-3p/PPARγ contributed to the premature senescence of these H2O2-induced HEI-OC1 cells. MiR-130b-3p regulated HEI-OC1 cell growth by targeting PPARγ, thus leading to ARHL.