New Way to See Single RNA Molecules

Photo: A cell in blue with the RNA molecules in red

Pinpointed: the RNA molecules are
made visible in red; © Philip
Santangelo/Georgia Tech

Techniques scientists currently use to image these transporters of genetic information within cells have several drawbacks, including the need for synthetic RNA or a large number of fluorescent molecules. The fluorescent probes developed at the Georgia Institute of Technology circumvent these issues.

"The probes we designed shine bright, are small and easy to assemble, bind rapidly to their targets, and can be imaged for hours. These characteristics make them a great choice for studying the movement and location of RNA inside a single cell and the interaction between RNA and binding proteins," said Philip Santangelo, an assistant professor at Georgia Tech and Emory University.

In the study, the probes – produced by attaching a few small fluorescent molecules called fluorophores to a modified nucleic acid sequence and combining the sequences with a protein – exhibited single-molecule sensitivity and allowed the researchers to target and follow native RNA and non-engineered viral RNA in living cells.

The researchers tested the sensitivity of conventional fluorescence microscopy to image individual probes inside a cell. Previous studies showed that these techniques were able to image an accumulation of probes inside a cell, but the current study demonstrated that individual probes without cellular targets could be observed homogenously distributed in the cytoplasm with no localization or aggregation.

Santangelo is currently trying to improve the probes by making them smaller and brighter, while also using them to investigate viral pathogenesis and other biological phenomena.

"We are excited to use this imaging strategy to study how single viral RNAs travel from the nucleus of a cell to a virus assembly site, how mRNAs are regulated by location and time, and RNA trafficking in neurons," added Santangelo.; Source: Georgia Institute of Technology