Clarin-1 mRNA expression in the central auditory system of Fischer Brown Norway rats.

Hereditary hearing loss is frequently linked to hair cell defects, even when the associated genes are expressed in the inner ear and other tissues including the brain. An example of this scenario is the clain-1 gene, associated with progressive loss of hearing in Usher syndrome type IIIA (USH3A). While mouse studies demonstrate that clarin-1 is an essential hair cell gene and early cochlear gene therapy shows promise, a comprehensive understanding of clarin-1's role in the auditory system may lead to better therapeutic and rehabilitation strategies for USH3A. To target future research effectively, we first mapped clarin-1 expression across central auditory system (CAS). We used small molecule fluorescent in situ hybridization (smFISH) to map clarin-1 mRNA expression in the central auditory nuclei of the rat brain. Our data reveal two key findings: clarin-1 mRNA is expressed in the cochlear nucleus (CN), inferior colliculus (IC), medial geniculate body (MG), and auditory cortex (AC). Also, the proportion of cells expressing clarin-1 varies across these regions, with the highest concentration in the IC. These results merit investigation of the role of clarin-1 in the nuclei of the CAS.