Knockout of dhx38 Causes Inner Ear Developmental Defects in Zebrafish

<b>Background</b>: Alternative splicing is essential for the physiological and pathological development of the inner ear. Disruptions in this process can result in both syndromic and non-syndromic forms of hearing loss. DHX38, a DEAH box RNA helicase, is integral to pre-mRNA splicing regulation and plays critical roles in development, cell differentiation, and stem cell maintenance. However, its specific role in inner ear development remains undefined. Here, we utilized a <i>dhx38</i> knockout zebrafish model to monitor the ear morphology and elucidate a crucial role for DHX38 in the development of the zebrafish inner ear. <b>Methods</b>: Bright-field morphological analysis and in situ hybridization were performed to observe ear morphology changes. Immunofluorescence and semi-quantitative RT-PCR were employed to test apoptotic cells and abnormal splicing. <b>Results</b>: The <i>dhx38^-/-</i> mutant zebrafish showed significant inner ear impairments, including decrescent otocysts, absent semicircular canal protrusion, and smaller otoliths. These structural abnormalities were accompanied by substantial DNA damage and p53-dependent apoptosis within the inner ear cells. Alternative splicing analysis showed that genes related to DNA damage repair and inner ear morphogenesis are abnormal in <i>dhx38</i> knockout mutants. In summary, we suggest that <i>dhx38</i> promotes cell survival during the inner ear development of zebrafish by ensuring the correct splicing of genes related to DNA damage repair.