Generation and characterization of a humanized GJB2 p.V37I knock-in mouse model for studying age-related hearing loss

Age-related hearing loss (ARHL) has been closely linked to genetic factors, with studies identifying the p.V37I mutation in the GJB2 gene as a potential contributor to ARHL. To investigate this, we generated a humanized p.V37I mutant mouse model and performed auditory brainstem response (ABR) testing, cochlear morphology assessments, and transcriptional sequence of mutant and wild-type (WT) mice at different ages. Our results indicated that this kind of GJB2 mutation does not lead to cochlear developmental abnormalities, and aging mutant mice exhibit only mild hearing loss compared to WT mice, without significant cochlear morphological differences. However, transcriptional analyses revealed substantial differences between mutant and WT mice. GO enrichment analysis of the DEGs between aging mutant and WT mice highlights significant enrichment in biological processes related to neural and sensory functions. Notably enriched terms include "neuron-to-neuron synapse," "immune response-activating signaling pathway," "regulation of synapse structure or activity," and "sensory perception of sound." These findings suggest that the p.V37I mutation in aging mice affects synaptic and calcium signaling pathways, as well as sensory system development. Despite these molecular changes, cochlear function remains normal in early life; however, as the mice age, hearing loss accelerates, likely due to a diminished capacity for gene-mediated protection against external stimuli.