Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2012 Jun 28;486(7404):541-4.
doi: 10.1038/nature11134.

Autoregulation of microRNA biogenesis by let-7 and Argonaute

Dimitrios G Zisoulis  1 , Zoya S Kai, Roger K Chang, Amy E Pasquinelli
Affiliations

Autoregulation of microRNA biogenesis by let-7 and Argonaute

Dimitrios G Zisoulis et al. Nature. .

Abstract

MicroRNAs (miRNAs) comprise a large family of small RNA molecules that post-transcriptionally regulate gene expression in many biological pathways. Most miRNAs are derived from long primary transcripts that undergo processing by Drosha to produce ~65-nucleotide precursors that are then cleaved by Dicer, resulting in the mature 22-nucleotide forms. Serving as guides in Argonaute protein complexes, mature miRNAs use imperfect base pairing to recognize sequences in messenger RNA transcripts, leading to translational repression and destabilization of the target messenger RNAs. Here we show that the miRNA complex also targets and regulates non-coding RNAs that serve as substrates for the miRNA-processing pathway. We found that the Argonaute protein in Caenorhabditis elegans, ALG-1, binds to a specific site at the 3′ end of let-7 miRNA primary transcripts and promotes downstream processing events. This interaction is mediated by mature let-7 miRNA through a conserved complementary site in its own primary transcript, thus creating a positive-feedback loop. We further show that ALG-1 associates with let-7 primary transcripts in nuclear fractions. Argonaute also binds let-7 primary transcripts in human cells, demonstrating that the miRNA pathway targets non-coding RNAs in addition to protein-coding messenger RNAs across species. Moreover, our studies in C. elegans reveal a novel role for Argonaute in promoting biogenesis of a targeted transcript, expanding the functions of the miRNA pathway in gene regulation. This discovery of autoregulation of let-7 biogenesis establishes a new mechanism for controlling miRNA expression.

PubMed Disclaimer

Conflict of interest statement

The authors declare no competing financial interests.

Figures

Figure 1
Figure 1. Argonaute binds and regulates pri-let-7
a, The let-7 gene: precursor sequence, two transcriptional start sites (A, B), splice site for SL1 trans-splicing and the ALG-1 binding site, which includes a let-7 complementary site (LCS), are indicated. b–c, Detection of the indicated transcripts by RIP of WT and alg-1(gk214) or HeLa cell extracts. d, Northern analysis of RNA from WT and alg-1(gk214). e–g, Levels of pri-let-7 relative to 18S rRNA and pre- or mature let-7 relative to 5.8S rRNA in WT or alg-1(gk214) quantified from d.
Figure 2
Figure 2. The ALG-1 binding site in pri-let-7 regulates expression of let-7
a, Detection of the indicated transcripts by RIP from two independent transgenic strains. b, Ratio of the levels of pri-let-7 inΔalg-1 versus WT determined by qRT-PCR and normalised to 18S rRNA. c, Northern analysis of RNA from WT orΔalg-1 pri-let-7 transgenes in let-7(mn112). d, Ratio of the levels of let-7 transcripts expressed fromΔalg-1 versus WT pri-let-7 transgenes in let-7(mn112) determined by qRT-PCR and normalized to 18S rRNA. e–f, Levels of pre- or mature let-7 relative to 5.8S rRNA expressed from WT or Δalg-1 pri-let-7 transgenes in let-7(mn112) quantified from c.
Figure 3
Figure 3. Mature let-7 regulates its own maturation
a, Base-pairing of mature let-7 to a site in pri-let-7 with the G→A mutation in let-7(n2853) indicated. b, Detection of the indicated transcripts by RIP of WT and let-7(n2853). c, Northern analysis of RNA from WT and let-7(n2853). d–f, Levels of pri-let-7 relative to 18S rRNA and pre- or mature let-7 relative to 5.8S rRNA in WT or let-7(n2853) quantified from c. g, Analysis of mature let-7(n2853) relative to 18S rRNA from the indicated strains or a 1:1 mix of RNA from let-7(n2853) and WT (mean ± s.e.m., n = 3, *, P < 0.05).
Figure 4
Figure 4. Association of ALG-1 with pri-let-7 in nuclear fractions
a, Detection in whole cell (W), nuclear (N) or cytoplasmic (C) fractions of the indicated proteins or RNAs (mean ± s.e.m., n = 3). b, Levels of the indicated transcripts relative to their respective inputs analysed by RIP and detected by qRT-PCR (mean ± s.e.m., n = 2). c, Ratio of mature let-7 from xpo-1 relative to control RNAi after normalization to 18S rRNA (mean ± s.e.m., n = 7, *, P < 0.001). d, Detection of the ALG-1 protein in fractions from WT and xpo-1-depleted animals. e, Analysis of pri-let-7 or 18S rRNA relative to their respective inputs by RIP and qRT-PCR of control (WT) or xpo-1 RNAi (mean ± s.e.m., n = 4, *, P < 0.001).
See this image and copyright information in PMC

Comment in

  • MicroRNAs micromanage themselves.
    Jiao A, Slack FJ. Jiao A, et al. Circ Res. 2012 Nov 9;111(11):1395-7. doi: 10.1161/CIRCRESAHA.112.281014. Circ Res. 2012. PMID: 23139285 Free PMC article.

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Suh N, Blelloch R. Small RNAs in early mammalian development: from gametes to gastrulation. Development. 2011;138:1653–1661. doi: 10.1242/dev.056234. - DOI - PMC - PubMed
    1. Kim VN, Han J, Siomi MC. Biogenesis of small RNAs in animals. Nat Rev Mol Cell Biol. 2009;10:126–139. doi: 10.1038/nrm2632. - DOI - PubMed
    1. Krol J, Loedige I, Filipowicz W. The widespread regulation of microRNA biogenesis, function and decay. Nat Rev Genet. 2010;11:597–610. doi: 10.1038/nrg2843. - DOI - PubMed
    1. Huntzinger E, Izaurralde E. Gene silencing by microRNAs: contributions of translational repression and mRNA decay. Nat Rev Genet. 2011;12:99–110. doi: 10.1038/nrg2936. - DOI - PubMed
    1. Fabian MR, Sonenberg N, Filipowicz W. Regulation of mRNA translation and stability by microRNAs. Annu Rev Biochem. 2010;79:351–379. doi: 10.1146/annurev-biochem-060308-103103. - DOI - PubMed

Publication types

MeSH terms