what is and what is the function of this RNA sequence

If you paid attention in science classes at school, names like DNA and RNA are no stranger to you, but new advances and discoveries in genetics have uncovered a specific type of RNA, microRNA or miRNA, which could represent major advances in medicine and the way we understand the functioning of living organisms.

The world of genetics is fascinating. Within every cell of everything living, two substances work together in extraordinary ways to preserve and execute the recipe for life: DNA and RNA.

DNA, known as the “instruction manual” of life, stores all the information necessary for the creation and maintenance of an organism.

On the other hand, RNA acts as a mediator, translating these instructions and guiding the process of manufacturing proteins, the essential ingredients that make the cell function.

But within this harmonious system, there is a special class of RNA molecules that plays an even more sophisticated role: microRNA (miRNA).

What is microRNA?

MicroRNA is a short RNA sequence, generally composed of around 20 to 25 nucleotides, that does not code for proteins, but exerts direct control over the translation of proteins from messenger RNA (mRNA).

It works as a regulator of gene expression, that is, it helps determine which genes will be activated or silenced. MiRNAs are produced within cells from primary RNA transcripts, which go through a maturation process until they become functional.

These molecules are present in practically all multicellular organisms and are highly conserved, indicating their evolutionary importance. Recent studies have shown that changes in the expression of microRNAs are related to several health conditions, making them targets of great interest for new therapies and medical diagnoses.

The importance of miRNAs was recognized in 2024, when a pair of scientists were awarded the Nobel Prize in Medicine for their discoveries in the field.

What is the function of microRNA?

The main role of microRNA is to regulate gene expression, interfering in the process of translating mRNA into proteins. This occurs because the miRNA specifically binds to mRNA molecules, promoting their degradation or inhibiting their translation. In this way, it acts as a biological “switch”, controlling protein levels in cells.

This regulation has a direct impact on several cellular functions, such as growth, differentiation, programmed cell death (apoptosis) and response to stress.

Furthermore, miRNAs play a crucial role in tissue development and maintenance, as well as the immune response.

On the other hand, dysregulation of microRNAs is associated with several diseases. For example, in certain types of cancer, overexpression or inhibition of specific miRNAs can promote tumor growth or prevent cancer cell death.

The methods behind the discovery of microRNAs

The discovery of microRNAs was the result of a pioneering study that combined RNA sequencing techniques with experimental models of simple organisms, such as the Caenorhabditis elegans. Scientists identified that small RNA molecules were involved in essential regulatory processes.

The study analyzed the interaction between miRNAs and mRNAs, demonstrating how these molecules could silence gene expression in a specific way. This approach has been documented in detail in scientific publications, including a recent paper in The Lancetwhich revisits the methods and impacts of this discovery on modern molecular biology.