Regulatory RNA Tiny RNA World Discovered

Two small temporal RNAs (stRNAs), let-7 and lin-4, play an important role in the development of the nematode Caenorhabditis elegans. Let-7 is also highly conserved throughout bilateral animals, including Drosophila and humans. Are there other small regulatory RNAs? Three reports by Lagos-Quintana et al., Lau et al., and Lee et al. indicate that there are a very large number (>60) of these tiny ~22-nucleotide microRNAs (miRNAs) and that they have molecular characteristics similar to the two known stRNAs. The miRNAs are developmentally and tissue-specifically expressed and are conserved between different organisms. Some of the RNAs are organized in an operon-like fashion and may be processed from a single precursor. In a Perspective, Ruvkun calls the RNAs the "biological equivalent of dark matter" and suggests that they may provide a potent means for regulating gene expression.

M. Lagos-Quintana, R. Rauhut, W. Lendeckel, T. Tuschl, Identification of novel genes coding for small expressed RNAs. Science 294, 853-858 (2001). [Abstract] [Full Text]

N. C. Lau, L. P. Lim, E. G. Weinstein, D. P. Bartel, An abundant class of tiny RNAs with probable regulatory roles in Caenorhabditis elegans. Science 294, 858-862 (2001). [Abstract] [Full Text]

R. C. Lee, V. Ambros, An extensive class of small RNAs in Caenorhabditis elegans. Science 294, 862-864 (2001). [Abstract] [Full Text]

G. Ruvkun, Glimpses of a tiny RNA world. Science 294, 797-799 (2001). [Full Text]