This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Information on what a cell did a few hours or days ago is generally unavailable to researchers, who can only measure the cell's current status. This is a problem if the aim is to understand how immune responses arise or why individual cancer cells survive treatment.
It is particularly revealing to know which genes in a cell are active, as this gives scientists key insights into how cells and the body work. To this end, they measure the RNA molecules—which are transcripts of the active genes but only ever provide a snapshot. However, this means that researchers can only record gene activity at the time of measurement.
Moreover, each cell can only be measured once, as the cell is destroyed when the RNA is collected and measured. Now, researchers at the Department of Biosystems Science and Engineering of ETH Zurich in Basel have developed a method that can be used to archive RNA molecules in cells. For the first time, this allows them to examine not only the current state of a cell, but also to reconstruct which genes were active in the past.
The work is published in the journal Nature Biotechnology. "Among other reasons, this glimpse into the past is of interest because it tells you about a cell's short-lived responses—of which there are many. Immune and stress responses are just a few examples," explains Christopher Reinkemeier, a postdoc in the group led by ETH professor Randall Platt.
In these short-lived responses, an external stimulus activates specific genes. As soon as the stimulus has passed, the cell shuts these genes down again. As part of a study, the researchers in Basel have shown how human cells in a cell culture respond to a signaling molecule of the immune system.
"If you measure too late with the conventional method, you no longer see that the response has even taken place," says Marcos Manero Carranza, a doctoral student in Platt's group and first author of the study alongside Reinkemeier. For the RNA archive inside the cells, the researchers need to capture RNA molecules and protect them against natural breakdown. This is because molecules of this kind are normally not made to last for long.
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