When and how was microRNA discovered?

MicroRNA was discovered in 1993 by Victor Ambros and his team at Harvard, studying gene regulation in the roundworm C. elegans. They found a small RNA molecule called lin-4 that regulated the lin-14 protein not by coding for another protein but by binding to and suppressing lin-14 mRNA — a completely unexpected mechanism. Gary Ruvkun's lab confirmed the complementary interaction. For several years, lin-4 was considered a curiosity unique to worms. In 2000, Ruvkun's lab discovered let-7, a second small regulatory RNA that was conserved across animals including humans — revealing that miRNA is a universal regulatory mechanism. By 2001, three papers in the same issue of Science described dozens of small RNAs in flies, worms, and humans, launching the miRNA field. Three decades later, over 80,000 papers have followed.