Trans-activation response (TAR) RNA-binding protein 2 is a novel modulator of transient receptor potential canonical 4 (TRPC4) protein

J Biol Chem. 2014 Apr 4;289(14):9766-80. doi: 10.1074/jbc.M114.557066. Epub 2014 Feb 21.


TRPC4 proteins function as Ca(2+) conducting, non-selective cation channels in endothelial, smooth muscle, and neuronal cells. To further characterize the roles of TRPC4 in vivo, detailed information about the molecular composition of native channel complexes and their association with cellular signaling networks is needed. Therefore, a mouse brain cDNA library was searched for novel TRPC4-interacting proteins using a modified yeast two-hybrid assay. This screen identified Trans-activation Response RNA-binding protein 2 (Tarpb2), a protein that recruits the Dicer complex to Ago2 for microRNA processing and gene silencing. Tarbp2 was found to bind to the C terminus of TRPC4 and TRPC5 and to modulate agonist-dependent TRPC4-induced Ca(2+) entry. A stretch of basic residues within the Tarbp2 protein is required for these actions. Tarbp2 binding to and modulation of TRPC4 occurs in the presence of endogenously expressed Dicer but is no longer detectable when the Dicer cDNA is overexpressed. Dicer activity in crude cell lysates is increased in the presence of Ca(2+), most probably by Ca(2+)-dependent proteolytic activation of Dicer. Apparently, Tarbp2 binding to TRPC4 promotes changes of cytosolic Ca(2+) and, thereby, leads to a dynamic regulation of Dicer activity, essentially at low endogenous Dicer concentrations.

Keywords: Calcium Signaling; Cell Signaling; Dicer; Protein-Protein Interactions; TRP Channels.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Argonaute Proteins / genetics
  • Argonaute Proteins / metabolism
  • Calcium / metabolism*
  • Cytosol / metabolism
  • DEAD-box RNA Helicases / genetics
  • DEAD-box RNA Helicases / metabolism
  • HEK293 Cells
  • Humans
  • Mice
  • MicroRNAs / biosynthesis*
  • MicroRNAs / genetics
  • RNA Processing, Post-Transcriptional / physiology*
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism*
  • Ribonuclease III / genetics
  • Ribonuclease III / metabolism
  • TRPC Cation Channels / genetics
  • TRPC Cation Channels / metabolism*


  • AGO2 protein, human
  • Ago2 protein, mouse
  • Argonaute Proteins
  • MicroRNAs
  • RNA-Binding Proteins
  • TRPC Cation Channels
  • TRPC4 ion channel
  • TRPC5 protein, human
  • Trpc5 protein, mouse
  • trans-activation responsive RNA-binding protein
  • DICER1 protein, human
  • Dicer1 protein, mouse
  • Ribonuclease III
  • DEAD-box RNA Helicases
  • Calcium