When our cells respond to stimuli or differentiate, they change their gene expression dramatically and modify RNA transcription to regulate their genes. One way to monitor gene regulation is to measure the levels of all RNAs by sequencing, but this has only been possible at single time points or across large cell populations. A new Nature Communications paper presents a novel method called ‘NASC-seq’ that can measure RNA synthesis in single cells simultaneously in two time points.

This drawing illustrates how this method allows to take a snapshot of both old and new RNA within a single cell. Newly synthesized and pre-existing RNA are distinguished by using a modified RNA base (4sU) that is incorporated only in new RNAs – shown by the highlighted red bases in the new RNA transcripts on the right side of the artwork.

This method will be useful for a large variety of applications, like investigating RNA dynamics or measuring changes in transcription during differentiation and development.

Congratulations Gert-Jan Hendriks, the Sandberg lab and the Cramer lab at Karolinska Institutet and Max Planck Institute for Biophysical Chemistry!

An RNA Snapshot of the Past and Present
A new method called ‘NASC-seq’ can distinguish old and new RNA in a single cell.