Identification of Novel Genes Coding for Small Expressed RNAs

We show that many 21- and 22-nt expressed RNAs, termed microRNAs, exist in invertebrates and vertebrates and that some of these novel RNAs, similar to let-7 small temporal RNAs, are highly conserved

Mariana Lagos-Quintana

2002

Scholarcy highlights

  • Two distinct pathways exist in animals and plants in which 21- to 23-nt RNAs function as posttranscriptional regulators of gene expression
  • 5Ј and 3Ј adapter molecules were ligated to the ends of a size-fractionated RNA population, followed by reverse transcription polymerase chain reaction amplification, concatamerization, cloning, and sequencing
  • Email: ttuschl@mpibpc.gwdg.de www.sciencemag.org SCIENCE VOL 294 26 OCTOBER 2001 identification of 21 novel human microRNAs, providing further evidence for the existence of a large class of small RNAs with potential regulatory roles. Because of their small size, and in agreement with the authors of two related papers in this issue, we refer to these novel RNAs as microRNAs
  • The expression profiles of miR-3 to miR-6 are highly similar, which suggests that a single embryo-specific precursor transcript may give rise to the different miRNAs or that the same enhancer regulates miRNA-specific promoters
  • The expression of mir-1 was detected by Northern blotting in total RNA from adult zebrafish and C. elegans, but not in total RNA from HeLa cells or mouse kidney
  • The challenge for the future is to define the function and the potential targets of these novel miRNAs by using bioinformatics as well as genetics and to establish a complete catalog of time- and tissue-specific distribution of the already identified and yet to be uncovered miRNAs. lin-4 and let-7 small temporal RNAs negatively regulate the expression of proteins encoded by mRNAs in which 3Ј untranslated regions contain sites of complementarity to the stRNA
  • A profound understanding of the expression, processing, and action of miRNAs may enable the development of more general methods to direct the regulation of specific gene targets and may lead to new ways of reprogramming tissues

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