Hsp90 regulates the function of argonaute 2 and its recruitment to stress granules and P-bodies

Mol Biol Cell. 2009 Jul;20(14):3273-84. doi: 10.1091/mbc.e09-01-0082. Epub 2009 May 20.

Abstract

Argonaute proteins are effectors of RNA interference that function in the context of cytoplasmic ribonucleoprotein complexes to regulate gene expression. Processing bodies (PBs) and stress granules (SGs) are the two main types of ribonucleoprotein complexes with which Argonautes are associated. Targeting of Argonautes to these structures seems to be regulated by different factors. In the present study, we show that heat-shock protein (Hsp) 90 activity is required for efficient targeting of hAgo2 to PBs and SGs. Furthermore, pharmacological inhibition of Hsp90 was associated with reduced microRNA- and short interfering RNA-dependent gene silencing. Neither Dicer nor its cofactor TAR RNA binding protein (TRBP) associates with PBs or SGs, but interestingly, protein activator of the double-stranded RNA-activated protein kinase (PACT), another Dicer cofactor, is recruited to SGs. Formation of PBs and recruitment of hAgo2 to SGs were not dependent upon PACT (or TRBP) expression. Together, our data suggest that Hsp90 is a critical modulator of Argonaute function. Moreover, we propose that Ago2 and PACT form a complex that functions at the level of SGs.

Publication types

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

MeSH terms

  • Animals
  • Antigens, Surface / metabolism
  • Argonaute Proteins
  • Benzoquinones / pharmacology
  • Cell Line
  • Cytoplasmic Granules / drug effects
  • Cytoplasmic Granules / metabolism*
  • Drosophila
  • Eukaryotic Initiation Factor-2 / metabolism*
  • Gene Silencing / drug effects
  • Green Fluorescent Proteins / metabolism
  • HSP90 Heat-Shock Proteins / antagonists & inhibitors
  • HSP90 Heat-Shock Proteins / metabolism*
  • Humans
  • Lactams, Macrocyclic / pharmacology
  • Mice
  • MicroRNAs / metabolism
  • Protein Binding / drug effects
  • Protein Transport / drug effects
  • RNA, Small Interfering / metabolism
  • RNA-Binding Proteins / metabolism
  • Recombinant Fusion Proteins / metabolism
  • Ribonuclease III / metabolism

Substances

  • AGO2 protein, human
  • Antigens, Surface
  • Argonaute Proteins
  • Benzoquinones
  • Eukaryotic Initiation Factor-2
  • HSP90 Heat-Shock Proteins
  • Lactams, Macrocyclic
  • MicroRNAs
  • PRKRA protein, human
  • RNA, Small Interfering
  • RNA-Binding Proteins
  • Recombinant Fusion Proteins
  • trans-activation responsive RNA-binding protein
  • Green Fluorescent Proteins
  • Ribonuclease III
  • geldanamycin