title: mRNA Decay of Most Arabidopsis miRNA Targets Requires Slicer Activity of AGO1.
abstract: MicroRNAs (miRNAs) are key posttranscriptional regulators of gene expression in animals and plants. They guide RNA-induced silencing complexes to complementary target mRNA, thereby mediating mRNA degradation or translational repression. ARGONAUTE (AGO) proteins bind directly to miRNAs and may catalyze cleavage (slicing) of target mRNAs. In animals, miRNA target degradation via slicing occurs only exceptionally, and target mRNA decay is induced via AGO-dependent recruitment of deadenylase complexes. Conversely, plant miRNAs generally direct slicing of their targets, but it is unclear whether slicer-independent mechanisms of target mRNA decay also exist, and, if so, how much they contribute to miRNA-induced mRNA decay. Here, we compare phenotypes and transcript profiles of ago1 null and slicer-deficient mutants in Arabidopsis (Arabidopsis thaliana). We also construct conditional loss-of-function mutants of AGO1 to allow transcript profiling in true leaves. Although phenotypic differences between ago1 null and slicer-deficient mutants can be discerned, the results of both transcript profiling approaches indicate that slicer activity is required for mRNA repression of the vast majority of miRNA targets. A set of genes exhibiting up-regulation specifically in ago1 null, but not in ago1 slicer-deficient mutants was also identified, leaving open the possibility that AGO1 may have functions in gene regulation independent of small RNAs.
authors.affiliation: Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark.
authors.forename: Laura
authors.identifier: 0000-0003-0605-0407
authors.initials: L
authors.lastname: Arribas-Hernández
authors.affiliation: Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark.
authors.forename: Lukasz Jan
authors.identifier: 0000-0001-5000-5561
authors.initials: LJ
authors.lastname: Kielpinski
authors.affiliation: Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark pbrodersen@bio.ku.dk.
authors.forename: Peter
authors.identifier: 0000-0003-1083-1150
authors.initials: P
authors.lastname: Brodersen
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000378:metabolism*; D060565:Argonaute Proteins / Q000378:metabolism*; D001483:Base Sequence; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D005799:Genes, Dominant; D019426:Integrases / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D014176:Protein Biosynthesis / Q000235:genetics; D020871:RNA Stability / Q000235:genetics*; D036226:Seedlings / Q000235:genetics; D017423:Sequence Analysis, RNA; D015854:Up-Regulation / Q000235:genetics
chemical_list: C117457:AGO1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D060565:Argonaute Proteins; D035683:MicroRNAs; C045073:Cre recombinase; D019426:Integrases