Casein kinase 1 and 2 phosphorylate Argonaute proteins to regulate miRNA-mediated gene silencing

EMBO Rep. 2023 Nov 6;24(11):e57250. doi: 10.15252/embr.202357250. Epub 2023 Sep 15.


MicroRNAs (miRNAs) together with Argonaute (AGO) proteins form the core of the RNA-induced silencing complex (RISC) to regulate gene expression of their target RNAs post-transcriptionally. Argonaute proteins are subjected to intensive regulation via various post-translational modifications that can affect their stability, silencing efficacy and specificity for targeted gene regulation. We report here that in Caenorhabditis elegans, two conserved serine/threonine kinases - casein kinase 1 alpha 1 (CK1A1) and casein kinase 2 (CK2) - regulate a highly conserved phosphorylation cluster of 4 Serine residues (S988:S998) on the miRNA-specific AGO protein ALG-1. We show that CK1A1 phosphorylates ALG-1 at sites S992 and S995, while CK2 phosphorylates ALG-1 at sites S988 and S998. Furthermore, we demonstrate that phospho-mimicking mutants of the entire S988:S998 cluster rescue the various developmental defects observed upon depleting CK1A1 and CK2. In humans, we show that CK1A1 also acts as a priming kinase of this cluster on AGO2. Altogether, our data suggest that phosphorylation of AGO within the cluster by CK1A1 and CK2 is required for efficient miRISC-target RNA binding and silencing.

Keywords: Argonaute; CK1A1; CK2; microRNA; phosphorylation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Argonaute Proteins / genetics
  • Argonaute Proteins / metabolism
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / metabolism
  • Caenorhabditis elegans Proteins* / genetics
  • Caenorhabditis elegans Proteins* / metabolism
  • Casein Kinase I / genetics
  • Casein Kinase I / metabolism
  • Gene Silencing
  • Humans
  • MicroRNAs* / genetics
  • MicroRNAs* / metabolism
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism
  • RNA-Induced Silencing Complex / genetics
  • RNA-Induced Silencing Complex / metabolism
  • Serine / metabolism


  • Argonaute Proteins
  • Caenorhabditis elegans Proteins
  • Casein Kinase I
  • MicroRNAs
  • RNA-Induced Silencing Complex
  • Serine
  • ALG-1 protein, C elegans
  • RNA-Binding Proteins

Associated data

  • GEO/GSE239453