Cloning and identification of microRNAs in bovine alveolar macrophages.

MicroRNAs (miRNAs) are a class of small non-coding RNAs found in both animal and plant cells. These approximately 19-26 nucleotide (nt) single-stranded RNAs play role in regulating gene/protein expression by either directly binding to mRNAs and inducing degradation of their target or by translational inhibition of protein expression. In this report, we described the cloning and identification of 22 microRNAs from bovine alveolar macrophage (AM). Eleven of the 22 miRNAs were novel and have not been previously identified in any species, while eight previously unidentified bovine miRNAs were identical to known ortholog miRNAs from human and/or rat (Bta-miR-141, Bta-miR-187, Bta-miR-191, Bta-miR-448, Bta-miR-589, Bta-miR-873, Bta-miR-463, and Bta-miR-562). These results add to the growing database of new miRNAs and suggest new biological functions for miRNAs in AMs. Specially, our data implicates miRNA regulation of antimicrobial targets in alveolar macrophages of bovine lung.