Little but loud: Small RNAs have a resounding affect on ear development

The impact of small RNA function has resonated throughout nearly every aspect of eukaryotic biology and captured the varied interests of researchers, whether they are endeavoring to understand the basis of development and disease or seeking novel therapeutic targets and tools. The genetic regulatory roles of microRNAs (miRNAs) are particularly interesting given that these often highly conserved factors post-transcriptionally silence many complementary target genes by inhibiting messenger RNA translation. In this regard, miRNAs can be considered as counterparts to transcription factors, the ensemble of which establishes the set of expressed genes that define the characteristics of a specific cell type. In this review, evidence supporting a resounding role for small RNAs in development and maturation of sensory epithelia in the mouse inner ear will be considered with an emphasis on the contribution of one hair cell miRNA family (miR-183, miR-96, and miR-182). Although there is much yet to be explored in this fledgling aspect of ear biology, the breadth of miRNA expression and functional requirement for ear development are already sounding off. (C) 2009 Elsevier B.V. All rights reserved