Molecular beacons and related probes for intracellular RNA imaging.

Accurately imaging endogenous or non-engineered RNA in live cells is not an easy task. Ideally, a probe and imaging strategy will have the following properties: (1) functional probes will be delivered to the desired cellular compartment, (2) they will achieve the correct level of affinity to bind target RNA efficiently but not inhibit their function, (3) be sensitive enough to allow for the accurate detection of the cellular RNA population, and (4) allow for the tracking of RNA through biogenesis, transport, translation, and degradation pathways. In this review, the capabilities of current nucleic acid-based probes and strategies used to image native RNA are discussed and analyzed, and probe and strategy recommendations for new users are given. The review is concluded by addressing topics for future research, all in the hope of achieving the ideal RNA imaging probe and strategy. (c) 2009 John Wiley & Sons, Inc.