By performing studies on cell cultures, CONICET researchers analyzed the key role of molecules discovered a few years ago, called “circular RNAs”, in the regulation of genetic expression. A study published in a prestigious journal nucleic acid research, contributes to the understanding of how these intracellular structures differ from the more “traditional” linear RNAs, which could be used in the future in the development of vaccines or to correct genetic changes that occur in various diseases of the central nervous system, infectious or neoplastic.
“Our work is part of basic research. However, as often happens with this type of risky and state-funded projects, basic research studies can, albeit unexpectedly, lead to the emergence of very valuable therapeutic technologies. The COVID-19 pandemic has taught us many things, including that RNA technology—which has enabled the development of many vaccines (making billions of dollars for the companies that developed them)—will be an essential biological tool for human and animal health. in the coming years,” says Manuel de la Mata, one of the study’s directors, CONICET researcher at the Institute of Physiology, Molecular Biology and Neurosciences (IFIBYNE, UBA–CONICET) and professor at the Faculty of Exact Sciences. and Naturals from the University of Buenos Aires (FCEyN).
In this sense, Damián Refojo, also director of advanced and CONICET researcher at the Biomedical Research Institute of Buenos Aires (IBioBA, dependent on CONICET and associated with the Max Planck Society of Germany), states that “those who drive these technologies, ” They will be , who will be better able to adapt to new therapies and even be able to develop new therapeutic strategies with consequent benefits for human or animal health, but also productive and commercial.”
circular RNA
In the 1960s, a coding ribonucleic acid (RNA) known as messenger RNA (mRNA) was discovered that acts as an intermediary between DNA and its final product, proteins, which are crucial for cell structure and function.
Genetic information “flows” from DNA to produce proteins: DNA is first “transcribed” in the form of mRNA, which is then “translated” in the form of proteins. There is a great variety of coding RNAs that are translated into different proteins in cells. Since 2000, however, it has been discovered that there is a vast and complex world of RNA molecules that no They are translated into proteins, but they also have essential functions for the cell. These are so-called non-coding RNAs, which can be short or long linear molecules or rarer species such as circular RNAs, which are the least known at the moment.
CWhat is the characteristic of circular RNAs that gives them their unique properties and what functions do they perform? These and other questions were to begin to be answered in La Mata and Refojo, which is why they decided to conduct a joint study.
In 2015, the Refojo laboratory published a joint study in the journal Molecular Celldirected by Dr. Nikolaus Rajewsky of the Max Delbruck Center in Berlin, Germany, where this type of circular RNA was first described to be highly expressed in the brains of various animals and even humans.
“Although the function of most of these circular RNAs is unknown, they represent a fertile area of study.” Today we already know that circular RNAs are more stable compared to linear RNAs and that some in particular perform important functions in different types of cells and tissues of the organism. However, the mechanisms by which these circular RNAs perform their function are far from understood,” says Refojo.
In addition, the researchers wanted to gather data on the interaction between circular RNAs and other types of non-coding RNAs called microRNAs. “MicroRNAs are small molecules that play a key role in the regulation of gene expression. They are known as “silencers” of gene expression. They work by binding to cognate sequences at the ends of messenger RNAs (mRNAs), inhibiting their translation into proteins or promoting their degradation,” explains de la Mata. And he continues: “The function of ‘switching off’ specific genes is essential for the normal functioning and development of organisms. Otherwise, changes occur that can lead to disease.”
Likewise, the normal functioning of cells and the organism requires that at a certain time microRNAs must be eliminated as soon as they have fulfilled their function by a process called TDMD (from the English “Targeted degradation of microRNAs“).
In this sense, de la Mata contributed significantly to the description of the TDMD phenomenon during his postdoctoral fellowship at the Friedrich Miescher Institute (FMI) in Basel, Switzerland, producing a scientific article in EMBO Reports (2015) and other related work. “TDMD is a very important cellular process, because by controlling the amount of microRNA, it also controls the amount of mRNA and ultimately proteins present in the cell,” explains the CONICET researcher.
Circular RNA and gene expression
The interaction between circular RNAs and microRNAs “is a particularly interesting area of research,” de la Mata suggests. And he adds: “Certain circular RNAs can sequester microRNAs, neutralizing their ability to regulate other messenger RNAs, thereby affecting the genetic regulatory network. “This mechanism may have significant implications in various biological processes and diseases.”
To reveal information about the interaction between circular RNAs and microRNAs, the authors of the study performed experiments on neurons obtained from the brains of mouse embryos and human cell lines. Using genetic engineering methods and bioinformatics analysis, CONICET researchers found that multiple circular RNAs affect the stability of various microRNAs. “Our results support the idea that circular RNAs influence TDMD, the process of degradation of specific microRNAs. In some cases this process of elimination improves and in others it hinders it. But the central point of our work was to demonstrate that two RNAs that have the same composition (that is, the same sequence of nucleotides or “letters”) and that differ only in that one is linear and the other circular, can have different effects. to TDMD, meaning that circularity itself can change the function of these RNAs,” says de la Mata.
“In the light of these results, we will begin to investigate the potential therapeutic use of these circular RNAs in various infectious, cancerous or central nervous system diseases,” adds Refojo.
“A better understanding of this type of molecule (circular RNA and microRNA) has, in my opinion, two possible consequences with enormous potential. The first is their use as tools in the biotechnological and pharmaceutical industries; the interest in finding applications for both types of RNA has exploded in recent years, from projects circular RNA vaccines to microRNA-based treatments for certain types of cancer. The second is about improving the way we understand the regulation of gene expression in cells, the potential uses of which are endless,” says Federico Fuchs, one of the first authors of the study, who participated in the work. . . We can only “fix” the things we understand, so a more detailed knowledge of the new types of regulations can allow us to find the cause of hitherto elusive diseases. new strategies for treatment development.”
“Understanding the regulation of gene expression is fundamental to understanding biological systems. In this scenario, circular RNAs are becoming increasingly popular, especially due to their abundance and their role in the brain. If we look deeper into his study, we can understand more details about the functioning of neurons, the brain and find clues about different diseases,” says Jerónimo Lukin, also the first author of the paper when he was a CONICET PhD student in the Refojo lab and now a scientist at the Icahn School of Medicine at Mount Sinai, New York, United States of America.
“We have already begun to investigate the development of vaccines based on circular RNAs and the possibility of detecting these molecules in blood and urine as a system for the early diagnosis of neurodegenerative diseases and cancer, therefore we have a good understanding of the properties that circularity gives them. RNA will allow us to better manipulate these molecular tools in the future,” concludes de la Mata.
The study involved collaboration with the laboratories of Jeremy Wilusz of Baylor College of Medicine in the United States and Gerhard Schratt of ETH-Zurich in Switzerland. With this latest lab, de la Mata and Refojo have received funding from the Swiss National Foundation (SNSF) to continue this line of research.
Bibliographic references:
Federico Fuchs Wightman, Jerónimo Lukin, Sebastián A Giusti, Michael Soutschek, Laureano Bragado, Berta Pozzi, María L Pierelli, Paula González, Juan P Fededa, Gerhard Schratt, Rina Fujiwara, Jeremy E Wilusz, Damián Refojo, Manuel de la Mata, Inla RNA circularity mats for target RNA-directed microRNA degradation, Nucleic acid research2024;, gkae094, https://doi.org/10.1093/nar/gkae094
Rybak-Wolf, A., Stottmeister, C., Glažar, P., Jens, M., Pino, N., Giusti, S., … & Rajewsky, N. (2015). Circular RNAs in the mammalian brain are highly abundant, conserved, and dynamically expressed. Molecular cell, 58(5), 870-885. https://doi.org/10.1016/j.molcel.2015.03.027
de la Mata, M., Gaidatzis, D., Vitanescu, M., Stadler, MB, Wentzel, C., Scheiffele, P., … & Großhans, H. (2015). Robust degradation of neuronal RNA induced by highly complementary targets. reports EMBO, 16(4), 500-511. https://doi.org/10.15252/embr.201540078
de la Mata, M., & Großhans, H. (2018). Turning the tables on miRNAs. Structural and molecular biology of nature, 25(3), 195-197. https://doi.org/10.1038/s41594-018-0040-x
