CURLY LEAF Regulates MicroRNA Activity by Controlling ARGONAUTE 1 Degradation in Plants

Mol Plant. 2020 Jan 6;13(1):72-87. doi: 10.1016/j.molp.2019.10.003. Epub 2019 Oct 10.


CURLY LEAF (CLF) encodes the methyltransferase subunit of the Polycomb Repressor Complex 2 (PRC2), which regulates the expression of target genes through H3K27 trimethylation. We isolated a new CLF mutant allele (clf-78) using a genetic screen designed to identify microRNA (miRNA) deficient mutants. CLF mutant plants showed impaired miRNA activity caused by increased ubiquitination and enhanced degradation of ARGONAUTE 1 (AGO1) in specific tissues. Such CLF-mediated AGO1 regulation was evident when plants were exposed to UV radiation, which caused increased susceptibility of clf mutants to some UV-induced responses. Furthermore, we showed that CLF directly regulates FBW2, which in turn triggers AGO1 degradation in the clf mutants. Interestingly, AGO1 bound to a target appeared particularly prone to degradation in the mutant plants, a process that was exacerbated when the complex bound a non-cleavable target. Thus, prolonged AGO1-target interaction seems to favor AGO1 degradation, suggesting that non-cleavable miRNA targets may overcome translation inhibition by modulating AGO1 stability in plants.

Keywords: ARGONAUTE; Arabidopsis; CURLY LEAF; FBW2; UV.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Arabidopsis / genetics*
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Argonaute Proteins / genetics
  • Argonaute Proteins / metabolism*
  • Gene Expression Regulation, Developmental
  • Gene Expression Regulation, Plant
  • Genes, Plant
  • Histones / metabolism
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism*
  • MicroRNAs / genetics*
  • Mutation
  • Phenotype
  • Plant Leaves / growth & development
  • Plant Leaves / metabolism
  • Polycomb-Group Proteins / metabolism


  • AGO1 protein, Arabidopsis
  • Arabidopsis Proteins
  • Argonaute Proteins
  • CURLY LEAF protein, Arabidopsis
  • Histones
  • Homeodomain Proteins
  • MicroRNAs
  • Polycomb-Group Proteins