New porcine microRNA genes found by homology search.

MicroRNAs (miRNAs) repress target genes at the post-transcriptional level and play important roles in development and cell lineage decisions. In vertebrates, however, both the targets of miRNAs and their expression profiles during development are poorly understood. Thus far, 326 human miRNAs, 249 mouse miRNAs, and 195 rat miRNAs have been identified. Even though the pig is a promising animal model in regenerative biology, as well as in livestock production, only 54 pig miRNAs have been identified. Here, we report the identification of 58 new pig miRNAs. We conducted a homology search using either human or mouse miRNAs genes queried against the pig genome. The new pig miRNAs consist of 23 miRNAs showing homology to mouse, 21 showing homology to human, and 16 showing homology to both human and mouse. The expression profile of 6 miRNAs were analyzed by Northern blot analysis isolated from porcine tissues: ovary, heart, kidney, liver, and pancreas.