The intracellular distribution and
dynamics of RNAs play
pivotal
roles in various physiological phenomena. The ability to monitor the
amount and localization of endogenous RNAs in living cells allows
for elucidating the mechanisms of various intracellular events. Protein-based
fluorescent RNA probes are now widely used to visualize and analyze
RNAs in living cells. However, continuously monitoring the temporal
changes in RNA localization and dynamics in living cells is challenging.
In this study, we developed a bioluminescent probe for spatiotemporal
monitoring of RNAs in living cells by using a split-luciferase reconstitution
technique. The probe consists of split fragments of a bioluminescent
protein, NanoLuc, connected with RNA-binding protein domains generated
from a custom-made mutation of a PUM-HD. The probe showed rapid luminescence
intensity changes in response to an increase or decrease in the amount
of a target RNA in vitro. In live-cell imaging, temporal
alteration of the intracellular distribution of endogenous β-actin
mRNA was visualized in response to extracellular stimulation. Furthermore,
the application of the probe to the visualization of the specific
localization of β-actin mRNA in primary hippocampal neurons
was conducted. These results demonstrate the capability of the bioluminescent
RNA probe to monitor the changes in localization, dynamics, and the
amount of target RNA in living cells.