Lmod3 ablation disrupts auditory function without compromising hair cell stereocilia development or MET competence.

F-actin cytoskeleton plays critical roles in hair cell. This study identifies LMOD3, an F-actin nucleator, as specifically expressed in outer hair cells (OHCs) of mice. Lmod3 knockout causes significant hearing loss (about 40 dB elevation in auditory brainstem response (ABR) thresholds, increased distortion product otoacoustic emission (DPOAE) thresholds), while leaving stereocilia morphology and mechanoelectrical transduction (MET) function intact. Phenotypic analyses hint that LMOD3 deficiency likely impairs OHC-based cochlear amplification. Our work establishes LMOD3 as essential for auditory function.