title: Cytoplasmic and nuclear quality control and turnover of single-stranded RNA modulate post-transcriptional gene silencing in plants.
abstract: Eukaryotic RNA quality control (RQC) uses both endonucleolytic and exonucleolytic degradation to eliminate dysfunctional RNAs. In addition, endogenous and exogenous RNAs are degraded through post-transcriptional gene silencing (PTGS), which is triggered by the production of double-stranded (ds)RNAs and proceeds through short-interfering (si)RNA-directed ARGONAUTE-mediated endonucleolytic cleavage. Compromising cytoplasmic or nuclear 5'-3' exoribonuclease function enhances sense-transgene (S)-PTGS in Arabidopsis, suggesting that these pathways compete for similar RNA substrates. Here, we show that impairing nonsense-mediated decay, deadenylation or exosome activity enhanced S-PTGS, which requires host RNA-dependent RNA polymerase 6 (RDR6/SGS2/SDE1) and SUPPRESSOR OF GENE SILENCING 3 (SGS3) for the transformation of single-stranded RNA into dsRNA to trigger PTGS. However, these RQC mutations had no effect on inverted-repeat-PTGS, which directly produces hairpin dsRNA through transcription. Moreover, we show that these RQC factors are nuclear and cytoplasmic and are found in two RNA degradation foci in the cytoplasm: siRNA-bodies and processing-bodies. We propose a model of single-stranded RNA tug-of-war between RQC and S-PTGS that ensures the correct partitioning of RNA substrates among these RNA degradation pathways.
authors.affiliation: Institut des Sciences du Végétal, CNRS UPR 2355, SPS Saclay Plant Sciences, 91198 Gif-sur-Yvette, France.
authors.forename: Ana Beatriz
authors.initials: AB
authors.lastname: Moreno
authors.forename: Angel Emilio
authors.initials: AE
authors.lastname: Martínez de Alba
authors.forename: Florian
authors.initials: F
authors.lastname: Bardou
authors.forename: Martin D
authors.initials: MD
authors.lastname: Crespi
authors.forename: Hervé
authors.initials: H
authors.lastname: Vaucheret
authors.forename: Alexis
authors.initials: A
authors.lastname: Maizel
authors.forename: Allison C
authors.initials: AC
authors.lastname: Mallory
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics; D029681:Arabidopsis Proteins / Q000378:metabolism; D002467:Cell Nucleus / Q000201:enzymology*; D003593:Cytoplasm / Q000201:enzymology*; D063326:Exosome Multienzyme Ribonuclease Complex / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D009154:Mutation; D059365:Nonsense Mediated mRNA Decay; D034622:RNA Interference; D020871:RNA Stability; D018749:RNA, Plant / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D018749:RNA, Plant; D063326:Exosome Multienzyme Ribonuclease Complex