Functional small RNAs are generated from select miRNA hairpin loops in flies and mammals Journal Article
| Authors: | Okamura, K.; Ladewig, E.; Zhou, L.; Lai, E. C. |
| Article Title: | Functional small RNAs are generated from select miRNA hairpin loops in flies and mammals |
| Abstract: | In the canonical animal microRNA (miRNA) pathway, Drosha generates ~60- to 70-nucleotide pre-miRNA hairpins that are cleaved by Dicer into small RNA duplexes that load into Argonaute proteins, which retain a single mature strand in the active complex. The terminal loops of some miRNA hairpins regulate processing efficiency, but once liberated by Dicer, they are generally considered nonfunctional by-products. Here, we show that specific miRNA loops accumulate in effector Argonaute complexes in Drosophila and mediate miRNA-type repression. This was unexpected, since endogenous loading of Argonaute proteins was believed to occur exclusively via small RNA duplexes. Using in vitro assays, which recapitulate Argonaute-specific loop loading from synthetic pre-miRNAs and even single-stranded oligoribonucleotides corresponding to miRNA loops, we reveal that the loop-loading mechanism is distinct from duplex loading. We also show that miRNA loops loaded into the miRNA effector AGO1 are subject to 3' resection, and structure-function analyses indicate selectivity of loop loading. Finally, we demonstrate that select miRNA loops in mammals are similarly loaded into Argonaute complexes and direct target repression. Altogether, we reveal a conserved mechanism that yields functional RNAs from miRNA loop regions, broadening the repertoire of Argonaute-dependent regulatory RNAs and providing evidence for functionality of endogenous ssRNA species. © 2013 by Cold Spring Harbor Laboratory Press. |
| Keywords: | controlled study; nonhuman; animal cell; mammalia; animals; mice; complex formation; microrna; genome-wide association study; drosophila; in vitro study; structure activity relation; animalia; gene expression regulation; conserved sequence; rna synthesis; mammal; gene repression; drosophila melanogaster; nucleic acid conformation; rna structure; micrornas; mammals; argonaute protein; drosophila proteins; short hairpin rna; argonaute 1 protein; double stranded rna; argonaute 2 protein; protein rna binding; single stranded rna; argonaute proteins; mirna hairpin loop; small rna loading |
| Journal Title: | Genes and Development |
| Volume: | 27 |
| Issue: | 7 |
| ISSN: | 0890-9369 |
| Publisher: | Cold Spring Harbor Laboratory Press |
| Date Published: | 2013-04-01 |
| Start Page: | 778 |
| End Page: | 792 |
| Language: | English |
| PROVIDER: | scopus |
| PMCID: | PMC3639418 |
| PUBMED: | 23535236 |
| DOI: | 10.1101/gad.211698.112 |
| DOI/URL: | |
| Notes: | --- - "Export Date: 1 May 2013" - "CODEN: GEDEE" - ":doi 10.1101/gad.211698.112" - "Source: Scopus" |
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