Analysis of miR-376 RNA cluster members in the mouse inner ear

Summary Mutations in phosphoribosyl pyrophosphate synthetase 1 (PRPS1) are associated with a spectrum of non‐syndromic to syndromic hearing loss. PRPS1 transcript levels have been shown to be regulated by the microRNA‐376 genes. The long primary RNA transcript of the miR‐376 RNA cluster members undergo extensive and simultaneous A → I editing at one or both of two specific sites (+4 and +44) in particular human and mouse tissues. The PRPS1 gene, which contains target sites for the edited version of miR‐376a‐5p within its 3′UTR, has been shown to be repressed in a tissue‐specific manner. To investigate whether the transcription of Prps1 is regulated by miR‐376 cluster members in the mouse inner ear, we first quantified the expression of the mature miR‐376 RNAs by quantitative real‐time‐PCR. The spatio‐temporal patterns of miR‐376 expression were assessed by in situ hybridization. Finally, we examined whether A →I editing of pri‐miR‐376 RNAs occurs in mouse inner ear by direct sequencing. Our data showed that the miR‐376a‐3p, b‐3p, c‐3p are present in mouse embryonic inner ears and intensive expression of miR‐376a‐3p/b‐3p was detected in the sensory epithelia and ganglia of both auditory and vestibular portions of the inner ear. In adult inner ear, the expression of miR‐376a‐3p/b‐3p is restricted within ganglion neurons of auditory and vestibular systems as well as the cells in the stria vascularis. Only unedited pri‐miR‐376 RNAs were detected in the cochlea suggesting that the activity of PRPS1 in the inner ear may not be regulated through the editing of miR‐376 cluster.