MiR-194 is involved in morphogenesis of spiral ganglion neurons in inner ear by rearranging actin cytoskeleton via targeting RhoB

• Published in: International journal of developmental neuroscience Vol. 63; no. 1; pp. 16 - 26
• Main Authors: Du, Jintao, Zhang, Xuemei, Cao, Hui, Jiang, Di, Wang, Xianren, Zhou, Wei, Chen, Kaitian, Zhou, Jiao, Jiang, Hongyan, Ba, Luo
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.12.2017; Elsevier BV
• Subjects: Actin; Actin Cytoskeleton - metabolism; Animals; Animals, Newborn; Bacterial Proteins - pharmacology; Bacterial Toxins - pharmacology; Cell Differentiation; Cells, Cultured; Cytoskeleton; Dendrites; Ear, Inner - cytology; Ear, Inner - embryology; Ear, Inner - growth & development; Embryo, Mammalian; Embryogenesis; Female; Fibers; Filaments; Ganglion cells; Gene Expression Regulation, Developmental - genetics; Inner ear; Male; Mice; Mice, Inbred C57BL; MicroRNAs; MicroRNAs - genetics; MicroRNAs - metabolism; miR-194; miRNA; Morphogenesis; Morphogenesis - drug effects; Morphogenesis - physiology; Neonates; Neurons; Oligonucleotides - genetics; Oligonucleotides - metabolism; Preservation; RhoB; rhoB GTP-Binding Protein - genetics; rhoB GTP-Binding Protein - metabolism; Ribonucleic acid; RNA; Sensory Receptor Cells - drug effects; Sensory Receptor Cells - metabolism; Spiral ganglion; Spiral Ganglion - cytology; Spiral ganglion neurons; Toxin B; Tubulin - metabolism; miR-194; Cytoskeleton; Spiral ganglion neurons; Inner ear; RhoB
• ISSN: 0736-5748; 1873-474X
• DOI: 10.1016/j.ijdevneu.2017.09.004

•For the first time, we demonstrated the dynamic spatiotemporal expression of miR-194 during inner ear development.•MiR-194 is involved in neuron morphogenesis by regulating the cellular cytoskeleton.•MiR-194 affects neuron morphogenesis through RhoB-mediated F-actin rearrangement. Many microRNAs participate in the development, differentiation and function preservation of the embryonic and adult inner ear, but many details still need to be elucidated regarding the numerous microRNAs in the inner ear. Based on previous investigations on the microRNA profile in the inner ear, we confirmed that several microRNAs are expressed in the inner ear, and we detected the spatial expression of these microRNAs in the neonatal mouse inner ear. Then we focused on miR-194 for its specific expression with a dynamic spatiotemporal pattern during inner ear development. Overexpression of miR-194 in cultured spiral ganglion cells significantly affected the dendrites of differentiated neurons, with more branching and obviously dispersed nerve fibres. Furthermore, the cytoskeleton of cultured cells was markedly affected, as disordered actin filaments resulting from miR-194 overexpression and enhanced filaments resulting from miR-194 knockdown were observed. Together with the bioinformatic methods, the RT-qPCR and western blot results showed that RhoB is a candidate target of miR-194 in the morphogenesis of spiral ganglion neurons. Additionally, the double luciferase reporter system was used to identify RhoB as a novel target of miR-194. Finally, the inhibition of RhoB activation by Clostridium difficile toxin B disturbed the organization of the actin filament, similar to the effects of miR-194 overexpression. In summary, we investigated microRNA expression in the mouse inner ear, and demonstrated that miR-194 is dynamically expressed during inner ear development; importantly, we found that miR-194 affects neuron morphogenesis positively through Rho B-mediated F-actin rearrangement.