What is MicroRNA? Nobel Prize-winning discovery explained

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The Nobel Prize in Medicine was awarded on Monday to two US scientists for the discovery of microRNA, a previously unknown type of genetic switch that it is hoped can pave the way for new medical breakthroughs.

But while several treatments and tests using microRNAs are being developed for cancer, heart disease, viruses and other diseases, none have actually reached patients yet.

And the world paid little attention when new Nobel laureates Victor Ambros and Gary Ruvkun revealed their discovery decades ago, thinking it was simply “something strange about worms,” ​​Cambridge University geneticist Eric Miska told AFP.

Here you can find out exactly how these tiny genetic switches work in our bodies.

Every cell in the human body has the same set of instructions, called DNA. Some turn into brain cells while others become muscles.

So how do cells know what to become? A process called gene regulation points to the relevant part of the DNA instructions.

Ribonucleic acid (RNA) normally serves as a messenger substance. It transmits DNA's instructions to proteins, the building blocks of life, that turn cells into brains – or muscles.

Miska cited as an example the messenger RNA vaccines introduced during the Covid-19 pandemic, which insert a message with new instructions on how to build proteins that block viruses.

But the two new Nobel Prize winners, Ambros and Ruvkun, discovered a completely new type of gene regulator that had previously been overlooked by science.

Rather than being the messenger that relays information, microRNA acts as a switch to turn other genes on and off.

“This was a whole new level of control that we had completely missed,” said Miska, who has been working on microRNA for two decades, including with the new Nobel laureates.

“The discovery of microRNAs brought an additional level of complexity by revealing that regions thought not to be coding play a role in gene regulation,” French researcher Benoit Ballester told AFP.

Back in the 1980s, Ambros and Ruvkun had been working independently on how genes interact in a millimeter-long roundworm called C.elegans.

When they compared their work, it led to the discovery of microRNA. Ambros revealed the finding in a 1993 paper.

“Nobody really paid much attention to it,” Miska said, explaining that most scientists at the time thought this only affected worms.

Then in 2000, Ruvkun published research showing that microRNA is present throughout the animal kingdom, including humans and even some viruses.

“This was not just something strange that worms do, but in fact all animals and plants are completely dependent on them for their development and normal functioning,” Miska said.

It is now assumed that there are more than a thousand genes in the human body that respond to microRNAs.

There are numerous new microRNA treatments and tests currently being tested, but none have been made widely available.

“Although there are no clear applications for microRNAs yet, understanding them, knowing that they exist, understanding their counter-regulatory networks is always the first step,” Gunilla Karlsson Hedestam of the Karolinska Institute told reporters in Stockholm.

MicroRNAs are particularly promising for fighting cancer because some of these switches “act as tumor suppressors, slowing down the inappropriate division of cells,” Miska said.

Others, however, “stimulate cells to divide, which can lead to cancer,” he added.

Because many viruses use microRNAs, several antiviral drugs are in different stages of development, including against hepatitis C.

To make matters worse, microRNAs can be unstable.

But scientists also hope that they can be used as so-called “biomarkers” that could, for example, provide information about which type of cancer a patient might be suffering from.

It is also likely that microRNAs could be involved in the evolution of our species, Miska said.

Although it is difficult to study human brains, Miska hopes that future research will find out even more.