Objective To determine the expression of miR-30b in hair cells of mice, and its regulatory effect on the target gene DNM1 and expression of Dynamin, the key protein of synaptic endocytosis in inner hair cells. Methods The basilar membrane of cochlear in adult C57 mice was obtained. The expression of miR-30b in the hair cells was detected by in situ hybridization. Luciferase vector was constructed and transfected into 293T cells with miR-30b. Changes in luciferase activity were measured to verify whether DNM1 was the target gene of miR-30b. Adeno-associated virus carrying miR-30b were micro-injected into cochlear via the round window membrane. mRNA expressions of DNM1 and miR-30b were detected by RT-PCR 14 days later. The expression of Dynamin was detected by Western blot. Results miR-30b expressed in the inner and outer hair cells scattered in the region of the nucleus and cytoplasm. miR-30b reduced luciferase activity from the reporter vector containing DNM11 (P<0.05), but not in its mutants. Increased expressions of miR-30b and decreased mRNA expressions of DNM1 and Dynamin were observed following transfection of AAV-miR-30b. Conclusion miR-30b expresses in inner and outer hair cells, which is consistent with the morphological orientation of dynamin. miR-30b inhibits the expression of Dynamin by targeting DNM11 gene.
