The SEBBM Journal is a channel for analysis, reflection and dissemination of scientific activity in Spain and of public and private research policies. Its origins date back to 1963 and it currently publishes thematic issues covering transversal research in the field of biochemistry and molecular biology. The articles are commissioned by the best specialists in the subject. Each issue also highlights the most relevant educational and scientific work of SEBBM members, as well as SEBBM news.
The current issue ‘RNA biology’ (nº 226, September 2025) has been coordinated by Dr. Encarnación Martínez-Salas from Centro de Biología Molecular Severo Ochoa (CBM), CSIC-UAM, Madrid, Spain.
‘It is unknown how many more secrets RNA holds, which is fascinating. Interestingly, at the molecular level, RNA exists in every conceivable conformation: single-stranded molecules with positive polarity (+ssRNA), negative polarity (-ssRNA), double-stranded (dsRNA), or covalently closed (circRNA). In addition, different types of RNA vary in length, structure, presence of atypical nucleotides (inosine) and/or post-transcriptional modifications (M7G, M6A, M5C, Ψ, etc.), which contribute to their stability, localisation, interaction with proteins and other cellular factors and, therefore, to their function.
RNA is the main actor in numerous cellular processes, in which it performs various key functions: catalyst (ribozymes: RNase P, rRNA, introns), genome (RNA viruses, viroids), structural particle (ribosomes, tRNAs, snRNAs, snoRNAs, SRP), regulator of RNA stability and translation (miRNAs, lncRNAs, asRNAs, UTRs), transmitter of the genome's coding capacity (mRNAs), therapeutic agent (RNA vaccines), etc. This diversity of activities is inherent to the plasticity and dynamism of its secondary and tertiary structure which, together with its sequence, synergistically increases its ability to recognise different ligands and perform different actions.
Understanding of the influence of chemical modifications on RNA, as well as the unexpected and surprising coding capacity of lncRNAs and circRNAs, is constantly advancing. In fact, the diversity of RNA structures and modifications has been key in the development of alternative strategies to regulate its function. Paradigmatic examples of the regulatory role of RNA modifications and structure are the M7GTP residue (known as the ‘cap’) of mRNA, or internal ribosome entry sites (IRES) that direct internal translation initiation. In eukaryotic organisms, most mRNAs are translated by a cap-dependent mechanism in a process regulated by several proteins, called eIFs. Defects or inhibition of protein synthesis have serious implications for physiological processes, such as the response to various types of stress, development, cell proliferation, or long-term memory. In these circumstances, the translation of atypical mRNAs, as well as some lncRNAs and circRNAs, is triggered by cap-independent mechanisms, a process involving RNA-binding proteins (RBPs), leading to the synthesis of specific proteins that are key to survival in certain cellular alert circumstances’.
Issue 226 of the SEBBM Journal contains four articles on various types of RNA molecules that have been recently discovered and that perform important functions:
Dr. Marcos de la Peña from the IBMPC, CSIC-UPV, Valencia, Spain presents a novel form of RNA called ‘obeliscos’ – small circular RNA molecules with replicating capacity, discovered in numerous organisms, which predominantly fold as double strands, similar to viroids. https://doi.org/10.18567/sebbmrev_226.202509.dc2
Dr. Pablo Manavella and Dr. Catharina Merchante from the IHSM ‘La Mayora’ at the University of Málaga-CSIC, Málaga, Spain describe the essential role of microRNAs in plant development, from their synthesis and maturation to their participation in the post-transcriptional regulation of different target mRNAs. https://doi.org/10.18567/sebbmrev_226.202509.dc3
Dr. Juan Carlos García-Soriano and Dr. Puri Fortes from the CIMA, Pamplona, Spain explain the coding capacity of certain long non-coding RNAs, whose name may be somewhat misleading. These RNAs, together with circular RNAs, represent a world of small molecules, overlooked in previous stages, with new functions yet to be explored. https://doi.org/10.18567/sebbmrev_226.202509.dc4
Dr. Sandra Blanco from the Instituto de Biología Molecular y Celular del Cáncer, CSIC - Universidad de Salamanca, Spain describes the astonishing regulatory capacity of gene expression determined by modifications (adenine and cytosine methylations, or the presence of pseudouridine) in RNA. https://doi.org/10.18567/sebbmrev_226.202509.dc5
The issue is available at https://sebbm.es/revista/numeros/biologia-del-arn/
Part of this post is a translation of text written in Spanish by Dr. Encarnación Martínez-Salas from Centro de Biología Molecular Severo Ochoa (CBM), CSIC-UAM, and published on the SEBBM website on September, 2025.
Reference:
Martínez-Salas E. 2025. El ARN: un actor versátil con múltiples formas y funciones. SEBBM 226, https://doi.org/10.18567/sebbmrev_226.202509.dc1