Spatiotemporal dynamics of microRNA during epithelial collective cell migration.

MicroRNAs (miRNAs) are small, noncoding RNAs variably involved in a wide variety of developmental and regenerative programs. Techniques for monitoring the spatiotemporal expression of miRNA in living cells are essential to elucidate the roles of miRNA during these complex regulatory processes. The small size, low abundance, sequence similarity, and degradation susceptibility of miRNAs, however, make their detection challenging. In this study, we detail a double-stranded locked nucleic acid (dsLNA) probe for detecting intracellular miRNAs during epithelial collective migration. The dsLNA probe is capable of detecting the dynamic regulation and dose-dependent modulation of miRNAs. The probe is applied to monitor the spatial distribution of miRNA expression of a migrating epithelium. Our results reveal a gradient of miRNA over the first one hundred microns from the leading edge and show the involvement of miR-21 in the complex regulation of transforming growth factor beta modulated epithelial migration. With its ease of use and capacity for real-time monitoring of miRNAs in living cells, the dsLNA probe carries the potential for studying the function and regulation of miRNA in a wide spectrum of complex biological processes.