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MicroRNAs and other tiny endogenous RNAs in C. elegans
Victor Ambros1, Rosalind C Lee, Ann Lavanway
1Dartmouth Medical School, Department of Genetics, Hanover, NH 03755, USA. vambros@dartmouth.edu
Current Biology : CB
|May 16, 2003
Summary
Researchers discovered three classes of small RNAs in C. elegans: microRNAs (miRNAs), tiny noncoding RNAs (tncRNAs), and endogenous small interfering RNAs (siRNAs). This suggests widespread gene regulation by RNA interference in worms.
Area of Science:
- Genomics
- Molecular Biology
- RNA Biology
Background:
- MicroRNAs (miRNAs) are small noncoding RNAs processed by Dicer, likely inhibiting mRNA translation via imprecise base-pairing.
- Small interfering RNAs (siRNAs) are similar in size but use precise complementarity for RNA-mediated interference (RNAi).
Purpose of the Study:
- To identify additional small RNAs in C. elegans with properties similar to miRNAs and siRNAs.
- To characterize the diversity of small RNA populations in C. elegans.
Main Methods:
- Utilized cDNA sequencing.
- Employed comparative genomics.
Main Results:
- Identified 21 new miRNA genes, estimating ~100 distinct miRNA genes in C. elegans, with 30% conserved in vertebrates.
- Discovered 33 tiny noncoding RNA (tncRNA) genes, similar in length to miRNAs but not phylogenetically conserved and lacking hairpin precursors.
- Found over 700 distinct small antisense RNAs, complementary to protein-coding regions, suggesting endogenous siRNAs involved in RNAi.
Conclusions:
- The presence of endogenous siRNAs indicates genome-wide gene silencing by RNAi in C. elegans.
- miRNAs and tncRNAs likely regulate gene activity through non-RNAi mechanisms due to lack of complete Watson-Crick complementarity.
- Diverse small RNA-mediated gene regulation mechanisms are employed in C. elegans.