title: miR-431 is involved in regulating cochlear function by targeting Eya4.
abstract: To understand the relationship between microRNAs and hearing loss and help clarify the causes of hereditary deafness, we studied the functions of miR-431 in cochleae. We first investigated the spatial-temporal expression profiles of miR-431 in spiral ganglion neurons (SGNs) in cochleae using real-time PCR and miRNA in situ hybridization. These studies showed that expression of miR-431 was high in SGNs in the cochleae of newborn mice, and decreased as development progressed. To test the functional effects of miR-431, we established miR-431 overexpressing transgenic (Tg) mice. Surface preparations of the cochlear basilar membrane and cochlear sections revealed no major structural differences between Tg and wild-type (Wt) mice. However, a comparison of auditory brain stem responses (ABRs) in Tg and Wt mice showed that ABR thresholds were significantly higher in Tg mice than in Wt mice. Notably, the density of SGNs was significantly lower in Tg mice than in Wt mice. We also found that the proportion of mature SGNs in cultures of primary SGNs from Tg cochleae was lower and their axons were shorter. A bioinformatics analysis predicted that the mRNA target of miR-431 was Eya4, a finding confirmed by luciferase reporter assays and western blotting. Importantly, overexpression of miR-431 in cochleae of Tg mice inhibited the translation of Eya4 mRNA, leading to a deficiency of EYA4. Thus, excessive amounts of miR-431 in cochleae of Tg mice may be the cause of sparse SGNs, which in turn could be responsible for hearing loss.
authors.affiliation: Department of Otolaryngology, Peking Union Medical College Hospital, Shuaifuyuan No.1, Beijing 100730, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Fan
authors.affiliation: Department of Otolaryngology, Peking Union Medical College Hospital, Shuaifuyuan No.1, Beijing 100730, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: The State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, 5 Dong Dan San Tiao, Beijing 100005, China.
authors.forename: Rimao
authors.initials: R
authors.lastname: Wu
authors.affiliation: Department of Otolaryngology, Peking Union Medical College Hospital, Shuaifuyuan No.1, Beijing 100730, China.
authors.forename: Xingming
authors.initials: X
authors.lastname: Chen
authors.affiliation: The State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, 5 Dong Dan San Tiao, Beijing 100005, China. Electronic address: dr_zhangyong@126.com.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Otolaryngology, Peking Union Medical College Hospital, Shuaifuyuan No.1, Beijing 100730, China. Electronic address: chenxw_pumch@163.com.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Chen
authors.affiliation: The State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, 5 Dong Dan San Tiao, Beijing 100005, China.
authors.forename: Dahai
authors.initials: D
authors.lastname: Zhu
keywords: Cochleae; Eya4; Spiral ganglion neuron; Transgenic mouse; miR-431