miRNAs in Bovine Genome: An Introduction

MicroRNAs (miRNAs) are small, endogenous, and evolutionarily conserved RNA molecules that regulate gene expression at the post-transcriptional level by binding to complementary sequences in messenger RNA (mRNA), resulting in translational repression and mRNA degradation. First identified in Caenorhabditis elegans in 1993, miRNAs have since been found to play pivotal roles in diverse biological processes across species, including cattle (Bos taurus). The bovine genome contains over 790 mature miRNAs, many of which are specific to cattle and are involved in the regulation of immune responses, inflammation, and host-pathogen interactions. Despite significant advances in profiling miRNA expression in bovine tissues, particularly in immune-related cells, the functional roles of miRNAs in regulating bovine immunity, particularly during viral infections, remain underexplored. Research to date has largely focused on bacterial infections, such as mastitis, where miRNA expression patterns have been shown to change in response to pathogens like Streptococcus uberis and Staphylococcus aureus. These findings suggest that miRNAs have potential as non-invasive biomarkers for disease detection and monitoring in cattle. Furthermore, miRNAs may serve as promising therapeutic targets for enhancing immune responses or combating infections in livestock. This review highlights the current state of bovine miRNA research, identifies key knowledge gaps, and proposes future directions for investigating miRNA-mediated regulation of immune function, their potential as diagnostic biomarkers, and their therapeutic applications in veterinary medicine.