MiR-183 family regulates chloride intracellular channel 5 expression in inner ear hair cells.

The roles of miRNAs in the onset of hearing and deafness are beginning to be revealed. Although there has been no reported link between chloride intracellular channel 5 (CLIC5) and the miR-183 family to date, we here present evidence that they are co-expressed in the inner ear and have functions that are related to stereocilia. Moreover, CLIC5 contains a single predicted and highly conserved miR-96/-182 binding site within its 3'-UTR. Our current results further show that miR-96/-182 and CLIC5 are co-expressed in HEI-OC1 cells, in which two isoforms of the CLIC5 protein exist. Furthermore, miR-96 and miR-182 were found to be specifically overexpressed in HEI-OC1 cells into which mimics of these molecules had been transfected by liposomes causing the downregulation of CLIC5 at both the mRNA and protein levels. Finally, miR-96/-182 specifically downregulate the expression of the luciferase reporter gene which was cloned into a mouse CLIC5 3'-UTR fragment containing the wild-type miR-96/-182 target sequence. Our findings thus suggest that CLIC5 is directly regulated by miR-96 and miR-182 and that the target sequence in this regard is located between nucleotides 760-766 within the CLIC5 3'-UTR.