Bioimaging of the unbalanced expression of microRNA9 and microRNA9* during the neuronal differentiation of P19 cells.

Generally, the 3'-end of the duplex microRNA (miR) precursor (pre-miR) is known to be stable in vivo and serve as a mature form of miR. However, both the 3'-end (miR9) and 5'-end (miR9*) of a brain-specific miR9 have been shown to function biologically in brain development. In this study, real-time PCR analysis and in vitro/in vivo bioluminescent imaging demonstrated that the upstream region of a primary miR9-1 (pri-miR9-1) can be used to monitor the highly expressed pattern of endogenous pri-miR9-1 during neurogenesis, and that the Luciferase reporter gene can image the unequal expression patterns of miR9 and miR9* seen during the neuronal differentiation of P19 cells. This demonstrates that our bioimaging system can be used to study the participation of miRs in the regulation of neuronal differentiation.