A study in which the Higher Council for Scientific Research (CSIC) has participated hasidentified the oldest known non-coding DNA sequences, some of which are present in both humans and coral relatives. The comparison of the genomes of multiple animals, distributed by the branches of the tree of life, has revealed that not only the proteins that build us, but also some of the instructions on how and where to use them were present in our ancestors for more than 550 million years. The study has been published in the latest issue of the journalProceedings of the National Academy of Sciences (PNAS).
“For more than 500 million years, evolution has been selecting ways to combine proteins, so that the organs and their physiology have changed through generations, giving rise to all the types of animals that live today or that existed in For this reason, one of the objectives of contemporary research in biology is to understand this combinatorial mechanism, its evolution, “explains CSIC researcher José Luis Gómez-Skarmeta, from the Andalusian Center for Developmental Biology.
Only 5% of vertebrate DNA is coding. This means that only a small part of the genome contains genes capable of generating RNA that serves as a messenger between DNA and the mechanisms that are responsible for making proteins.The remaining 95% of non-coding DNA has been called junk DNA for many years.
? Of the proteins from this 5%, only a part, the so-called transcription factors, are in charge of controlling the expression of other genes, that is, the production of all the tools of the genome. Thus, each cell type, for example a neuron, expresses a set of transcription factors that, by regulating the expression of the genome, makes the neuron produce everything that makes it function as such ?, says CSIC researcher Fernando Casares, also from the Andalusian Center for Developmental Biology. Clues to understand the past
Non-coding DNA, “unfairly labeled junk DNA”According to the researchers, it contains the regulatory regions that control when, how, in what quantity and where RNA should be generated from DNA, a process called gene transcription.
“These regulatory regions are DNA sequences that act as molecular landing strips for combinations of transcription factors. Each cell type, throughout its differentiation, expresses different combinations. If the track is available and the specific combination is present in the cell, the transcription factors will “land.” In this way, certain proteins will be produced and others will not. Thus, these regulatory regions hold the key to understanding the past, present and, perhaps, the future of the cells of an individual. organism “, point the researchers of the CSIC.
During the investigation, tests were carried out in different organisms, such as sea urchins, fruit flies and zebrafish, which demonstrated that one of the identified non-coding DNA sequences induced the expression of neurons in the process of differentiation in all these organisms. “If the tools are to a large extent universal, the evolution of organisms must be based, also to a large extent, on changes in the combination of transcription factors and the regulatory sequences to which they bind. If humans we have a mechanism that corals also have, probably our common ancestors also had it hundreds of millions of years ago “, concludes Gómez-Skarmeta.
