The 2024 Nobel Prize in Physiology or Medicine has been awarded to the co-discoverers of microRNAs (miRNAs), a ground-breaking discovery that has transformed our understanding of gene regulation. But what exactly are miRNAs, and why is this recognition so important?

What are miRNAs?

MicroRNAs (miRNAs) are a type of gene, but not ordinary genes in the traditional sense. When people talk about ‘genes’ what is usually being referred to are protein-coding genes – sequences in our DNA that are the instructions for cells to make a protein, such as haemoglobin or insulin. Instead, miRNAs play a regulatory role, controlling how and when proteins are made in our cells.

How do miRNAs work?

Imagine miRNAs as molecular Velcro, sticking to mRNA messages to block them from reaching the protein-production machinery inside our cells, known as the ribosome which an earlier Nobel prize went to. This is a bit like tying a knot in a shoelace to stop it from being threaded through. By controlling this process, miRNAs ensure that proteins are made at the right time and in the right amounts.

What do miRNAs do for our bodies?

By regulating networks of genes, they help our cells function properly. miRNAs are especially important in the brain, which contains the highest levels of active miRNAs. miRNA genes are always busy, working inside cells from the moment of fertilisation throughout every moment of our lives until we die.

‘Master controllers’ of gene expression

miRNAs are sometimes referred to as ‘master controllers’ or ‘conductors of the molecular orchestra’ because each miRNA can stick to dozens of these protein-coding mRNAs. That makes them very powerful or influential, controlling virtually every process inside our cells.

Why do we need miRNAs?

Regular gene activity can be noisy and unstable, but miRNAs provide a stabilising effect, offering negative feedback to keep things in balance and cells functioning properly. miRNAs evolved early in the history of life and have helped organisms, including humans, develop more complex gene activity patterns. Remarkably, while humans and the worm C. elegans (where miRNAs were first discovered) have a similar number of protein-coding genes, humans have 25 times more miRNA genes. So, more miRNAs mean greater complexity! Our brains have some primate and human-specific miRNA genes.

Applications of the discovery

The discovery of miRNAs has paved the way for significant advancements in medicine. miRNAs are now used to develop blood tests for cancers, and scientists are exploring their potential as therapeutic targets in various human diseases.

Irish Contributions to miRNA Research

Here in Ireland, researchers are at the forefront of miRNA research, studying their role in human disease and exploring their potential as treatments or biomarkers. At FutureNeuro, miRNAs are a cornerstone of our research. One exciting project involves developing a miRNA-based drug to treat epilepsy, a testament to the far-reaching impact of this Nobel prize-winning discovery.

If you’re interested in learning more about the fascinating role of microRNAs in shaping our biology, check out Fine-Tuning Life: A Guide to MicroRNAs, Your Genome’s Master Regulators, the new book by our Centre Director, Prof David Henshall.