Novel_circ_0004013 targeting miR-29a-3p affects age-related hearing loss in miR-29a mouse model by RNA-seq analysis

Age-related hearing loss (ARHL) is a gradual, symmetrical sensorineural disorder. Exploring the pathogenesis of ARHL from a biological perspective is important for its treatment. In this study, we analyzed the circRNA expression profiles of 2-month-old miR-29a^+/+ mice and miR-29a^-/- mice by transcriptome sequencing to investigate the role of circRNAs in ARHL. We identified 12 differentially expressed circRNAs in the two groups. Our focus was on circRNAs predicted to regulate miR-29a, with novel_circ_0004013 identified as having a targeted binding relationship with miR-29a-3p. Dual luciferase assays confirmed that miR-29a-3p is a direct target of novel_circ_0004013. Fluorescence in situ hybridization (FISH) was employed to localize the novel_circ_0004013 in HEI-OC1 cells and the cochlea. Novel_circ_0004013 was mainly expressed in the cytoplasm. In the hair cells (HCs) and stria vascularis (SV) regions of miR-29a^-/- mice, novel_circ_0004013 expression was higher than the corresponding regions in miR-29a^+/+ mice. Furthermore, Western blot assays revealed that levels of oxidative stress and apoptosis were significantly decreased in HEI-OC1 cells following the knockdown of novel_circ_0004013, whereas these levels were significantly increased in HEI-OC1 cells after the knockdown of miR-29a-3p. It was indicated in rescue assays that novel_circ_0004013 expedited oxidative stress and apoptosis of HEI-OC1 cells via modulation on miR-29a-3p. These findings may reveal the important role of novel_circ_0004013 in hearing loss and provide a new perspective and theoretical basis for the molecular mechanism of ARHL.