Screening and identification of synaptic regulatory genes in the inner ear of mice with presbycusis

Abstract

Objective To screen synaptic regulatory genes in the inner ear and explore the mechanism of synaptic damage in presbycusis. Methods We examined the mRNA expression of the genes in the basilar membrane of the inner ear of adult (4-week-old) mice and aged (40-week-old) mice using transcriptome sequencing. Gene Ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment of the differentially expressed genes (DEGs) were analyzed to identify synaptic regulatory DEGs, and the results were verified using real-time quantitative PCR and immunofluorescence staining. Results We identified a total of 3 267 DEGs, including 1 521 down-regulated genes and 1 746 up-regulated genes (FC≥1.5, P < 0.05). GO function enrichment analysis showed that the down-regulated DEGs mainly participated in the regulation of voltage-gated cation channel activity and synaptic function, and the up-regulated DEGs were mostly responsible for regulation of immune functions. We screened 64 synaptic regulatory genes, among which 6 down-regulated potassium channel genes (Kcnq2, Kcnk3, Kcnmb4, Kcnk9, Kcnh5, and Kcnc2) had the highest enrichment. qRT-PCR verified the differential expression of the 6 genes in the inner ear of mice at different ages; immunofluorescence assay demonstrated that the expression of KCNQ2 and KCNMB4 were significantly decreased in the inner ear of aged mice. Conclusion Among the synaptic regulatory genes screened in mice with presbycusis, 6 potassium channel genes show significantly decreased expressions in the inner ear of aged mice, suggesting their important involvement in synaptic changes in presbycusis.

Keywords

• presbycusis
• inner ear
• synapse
• transcriptome sequencing
• potassium channel