Dual optical biosensors for imaging microRNA-1 during myogenesis

Dual optical microRNA (miRNA) imaging systems, bioluminescent reporter gene (a signal-off mechanism)- or fluorescent molecular beacon (MB) (a signal-on mechanism)-based miRNA imaging system, have individually allowed us to sense miRNA biogenesis in a noninvasive and iterative manner. Both of these imaging systems have shortcomings with respect to image quality. Therefore, we designed a dual optical imaging systems by simultaneous imaging of a miRNA-1 reporter gene (CMV/Gluc/3xPT_miR-1) and miRNA-1 MB in a single cell to overcome these limitations and used it to visualize miRNA-1, a highly expressed miRNA in cardiac and skeletal muscle. During myogenic differentiation of C2C12 cells, the bioluminescence intensity from CMV/Gluc/3xPT_miR-1 revealed a miRNA-1-dependent gradual decrease and the fluorescence intensity from miR-1 MB demonstrated a miRNA-1-dependent gradual increase both in vitro and in vivo. The dual miRNA-1 imaging systems, which provides the complementary imaging information about miRNA biogenesis, could be useful to sense miRNA expression during various biologic processes.