You won't believe these 10 facts about people. MicroRNA, or miRNA, is a type of molecule that plays an important role in post-transcriptional gene regulation.Most ribonucleic acid (RNA) serves as an intermediary between deoxyribonucleic acid (DNA), which stores genetic information, and proteins, which typically express the genetic information.ou won't believe these 10 facts about people. MicroRNA, or miRNA, is a type of molecule that plays an important role in post-transcriptional gene regulation.