Hearing loss is caused by many factors including ototoxic drug-induced hair cell damage. Ombuoside, an antioxidant isolated from Gynostemma pentaphyllum, has been suggested to serve as a new neuroprotective drug. However, the role of ombuoside in protecting inner ear hair cells from ototoxic drug-induced damage has not been investigated. Here, we demonstrated the protective potential of ombuoside in mitigating drug-induced ototoxicity in vivo and in vitro. We used cisplatin, a highly ototoxic anti-tumor drug, to induce hair cell damage. Our results showed that ombuoside significantly increased the survival of cisplatin-treated HEI-OC1 cells. Further mechanism research suggested that ombuoside protects HEI-OCI cells from cisplatin-induced apoptosis by reducing the cisplatin-induced upregulation of apoptosis-promoting proteins Bax, Bak, as well as apoptosis indicator proteins cytochrome C and cleaved-caspase-3, and the downregulation of apoptosis-inhibiting proteins Bcl-2. Ombuoside also protects the cells from the excessive ROS production and mitochondrial membrane depolarization triggered by cisplatin. These results demonstrated the potential for ombuoside in protecting hair cells from cisplatin by suppressing ROS generation and the mitochondrial apoptotic cascade. Ombuoside showed promise in protecting hair cells from cisplatin-induced apoptosis by suppressing ROS generation and the mitochondrial apoptotic cascade. Furthermore, ombuoside co-treatment in mouse cochlear explants and zebrafish lateral neuromasts rescued the decreased number and deformed morphology of hair cells resulting from cisplatin exposure. These findings further validated our conclusions and indicated that ombuoside is a potential protector against hearing loss caused by ototoxicity as a clinical side effect of cisplatin.

Toe1 (target of EGR1, member 1) is a 3′- exonuclease in the deadenylase family, essential for the maturation of small nuclear RNAs. Mutations in Toe1 are linked to pontocerebellar hypoplasia 7 (PCH7), a severe neurodegenerative syndrome affecting infants, characterized by progressive neurodegeneration, developmental delay, and genital abnormalities. The pathogenic mechanisms of PCH7 are unclear but are thought to involve abnormal neural stem cell (NSC) development during embryogenesis. This study investigates Toe1's role in NSC development using the C17.2 NSC line. Colony formation, EdU incorporation, and CFSE staining assays showed that Toe1 knockout inhibited C17.2 cell proliferation. Upon inducing differentiation, Toe1 knockout significantly reduced cell dendrites. Immunofluorescence, qPCR, and Western blot analyses indicated that Toe1 knockout suppressed the expression of neuronal marker βIII-tubulin and glial cell marker Gfap, thereby inhibiting C17.2 cell differentiation. Additionally, Toe1 knockout reduced the expression of Dll1 and Jag1, suggesting an inhibition of Notch signaling. High-throughput transcriptome sequencing revealed that Toe1 influenced calcium ion binding, ECM, and amino acid catabolism in undifferentiated C17.2 cells, and peptidase activity, chemotactic factors, ECM, and TNF signaling in differentiated cells. These findings underscore Toe1's critical regulatory role in NSC proliferation and differentiation, with significant implications for developing therapeutic targets for neurodegenerative diseases such as PCH7.