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The Nobel Prize in Physiology or Medicine 2024 has been awarded to Victor Ambros and Gary Ruvkun for their discovery of microRNAs, small regulators of gene expression.

On October 7, the Nobel Assembly at the Karolinska Institute awarded the 2024 Nobel Prize in Physiology or Medicine to Victor Ambros (born 1953) and Gary Ruvkun (born 1952), two American biologists, for their "discovery of microRNAs and their role in the post-transcriptional regulation of gene expression." This discovery, made in 1993, profoundly transformed the understanding of various biological mechanisms, challenging the traditional dogmas that governed gene expression regulation. While molecular genetics research primarily focused on genes (and therefore DNA) and proteins, these researchers demonstrated that microRNAs play an equally fundamental role in controlling gene expression. Collaborating while separately studying a one-millimeter roundworm, Caenorhabditis elegans (commonly known as C. elegans), they aimed to understand the reasons and precise moments of cellular mutations, as explained by the Nobel committee in its announcement.

Regulation Process

To grasp the significance of this discovery, it is crucial to examine the gene expression process. DNA, which contains genetic information, is first transcribed into messenger RNA (mRNA), which is then translated into proteins. These proteins play structural roles (as in muscle tissues, for example) and functional roles (in various biological activities, particularly through enzymes, antibodies and hormones). MicroRNAs are small RNA molecules that bind to specific mRNAs to inhibit their translation into proteins or induce their degradation. This regulatory process is essential because it allows cells to quickly adjust protein production according to their physiological needs.

Ancient but Conserved Mechanism

The role of microRNAs is rooted in an evolutionary history spanning hundreds of millions of years. Research has shown that these molecules are present in almost all multicellular organisms, highlighting their fundamental role in cellular biology. This regulatory mechanism has enabled the emergence of increasingly complex organisms by allowing fine control of gene expression. Over the past two decades, research on microRNAs has highlighted their critical role in the normal development of cells and tissues. Studies indicate that microRNAs are crucial for embryonic development, as they inhibit the production of certain proteins, which is essential for precise regulation of cellular development processes. Furthermore, anomalies in microRNA regulation can lead to various pathologies, ranging from cancers to metabolic diseases, as well as neurodegenerative disorders and autoimmune diseases.

Clinical Implications

The discovery of microRNAs has major implications in the medical field, offering new perspectives for the treatment of various diseases. However, no immediate applications have yet been implemented. Mutations in the genes coding for these molecules have been linked to several human diseases. For instance, studies have identified mutations in specific microRNAs that contribute to disorders such as congenital hearing loss and skeletal abnormalities. The DICER1 syndrome, a rare disorder related to mutations in a gene essential for microRNA production, is another example of the impact these molecules have on human health. This hereditary tumor predisposition syndrome is associated with an increased risk of developing cancers in multiple organs, again highlighting the importance of microRNAs in regulating cell growth.

Therapeutic Arsenal

MicroRNAs are also being studied as potential biomarkers for the early diagnosis of various diseases. Their presence or expression levels could provide insights into an individual’s pathological state. A study published in August 2021 by Elsevier suggested that microRNAs could serve as biomarkers for severe Covid-19. Additionally, the possibility of leveraging these molecules as therapeutic tools opens new avenues for developing innovative treatments. In the future, therapies based on microRNAs could become essential components of the therapeutic arsenal to combat complex diseases such as cancer, autoimmune disorders and neurodegenerative diseases.

Last year, the Nobel Prize in Medicine recognized the work of Hungarian researcher Katalin Kariko and her American colleague Drew Weissman, who were pivotal in developing mRNA vaccines, which were crucial in the fight against Covid-19. "These are two very different awards; however, a fundamental understanding is certainly the first step toward developing applications," noted Gunilla Karlsson Hedestam, a professor at the Karolinska Institute.