Identification of stria vascularis cell type profile by single-cell RNA-sequencing in the adult mouse model of Pendred syndrome. undefined

The primary pathological alternations of SLC26A4-related hearing loss are endolymphatic pH acidification and luminal enlargement of the inner ear. However, the molecular cell type-specific influences remain poorly characterized. In this study, we confirmed a method of isolating single cells in the cochlea's stria vascularis (SV) from wild-type (WT) animals. We then applied it to characterize the distinct transcriptomes from mutant (Slc26a4+/- and Slc26a4-/-) samples. Single-cell RNA-sequencing (scRNA-seq) identified transcriptional profiles in Slc26a4-expressing (spindle) cells and Kcnj10-expressing (intermediate) cells of the SV. By Gene Set Enrichment Analysis (GSEA), we found that spindle cells contain extrinsic cellular components, a factor that enables cell-to-cell communication. In addition, the gene expression profile informed signaling pathways associated with pH regulation in spindle cells. Compared to WT control, the transcriptional profiles in the SV cells of Slc26a4-/- mice showed downregulation of extracellular exosome-related genes in spindle cells and GPI-anchor-related genes in the intermediate cells. Immunofluorescence studies in spindle cells of Slc26a4-/- mice validated the increased expression of the clathrin-mediated endocytosis-related protein. Overall, cell isolation of SV from WT and mutant (Slc26a4+/- and Slc26a4-/-) samples combined with cell type-specific transcriptomic analyses revealed pH-dependent alternations in spindle cells and intermediate cells, inspiring further studies into the dysfunctional role of SV cells in SLC26A4-related hearing loss.