Non-Coding RNAs and Their Regulatory Roles

Non-coding RNAs (ncRNAs) are a complex family of regulatory RNAs that modulate the flow of genetic information from DNA to protein at multiple levels. Rather than encoding proteins, these RNAs work as regulators of gene expression, forming intricate networks that operate in parallel with the canonical transcriptional and translational machinery. Their regulatory roles are essential for preserving cellular homeostasis and are particularly prominent in complex multicellular organisms, where they contribute to the fine-tuning of diverse physiological processes. In this chapter, we explore the historical milestones that led to the recognition of ncRNAs as functional genomic elements and provide an overview of the major ncRNA classes. Special attention is given to microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), three distinct families that exhibit unique biogenesis pathways, mechanisms of action, and regulatory roles. Each ncRNA class will be discussed in detail, focusing on their molecular origin, regulatory strategies, and involvement in selected biological contexts that highlight their relevance in cellular regulation.