title: AGO1 homeostasis entails coexpression of MIR168 and AGO1 and preferential stabilization of miR168 by AGO1.
abstract: Arabidopsis ARGONAUTE1 (AGO1) encodes the RNA slicer enzyme of the microRNA (miRNA) pathway and is regulated by miR168-programmed, AGO1-catalyzed mRNA cleavage. Here, we describe two additional regulatory processes required for AGO1 homeostasis: transcriptional coregulation of MIR168 and AGO1 genes, and posttranscriptional stabilization of miR168 by AGO1. Disrupting any of these regulatory processes by using mutations or transgenes disturbs a proper functioning of the miRNA pathway. In contrast, minor perturbation leads to fine-tuned posttranscriptional adjustment of miR168 and AGO1 levels, thereby maintaining a proper balance of other miRNAs, which, together with AGO1, control the mRNA levels of miRNA targets. We suggest that miR168 stabilization occurs at the level of silencing-complex assembly and that modulating the efficiency of assembling miRNA-programmed silencing complexes will also be important in other contexts.
authors.affiliation: Laboratoire de Biologie Cellulaire, Institut Jean-Pierre Bourgin, INRA, 78026 Versailles Cedex, France. herve.vaucheret@versailles.inra.fr
authors.forename: Hervé
authors.initials: H
authors.lastname: Vaucheret
authors.forename: Allison C
authors.initials: AC
authors.lastname: Mallory
authors.forename: David P
authors.initials: DP
authors.lastname: Bartel
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D060565:Argonaute Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D006706:Homeostasis; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D030821:Plants, Genetically Modified; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D018749:RNA, Plant / Q000235:genetics*; D034743:RNA-Induced Silencing Complex; D043244:Ribonuclease III / Q000378:metabolism; D019076:Transgenes / Q000502:physiology
chemical_list: C117457:AGO1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D060565:Argonaute Proteins; D018797:Cell Cycle Proteins; D035683:MicroRNAs; D012333:RNA, Messenger; D018749:RNA, Plant; D034743:RNA-Induced Silencing Complex; C402383:DCL1 protein, Arabidopsis; D043244:Ribonuclease III