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Updated: Apr 20, 2026

Studying RNA Interactors of Protein Kinase RNA-Activated during the Mammalian Cell Cycle
Published on: March 5, 2019
Deletion of human tarbp2 reveals cellular microRNA targets and cell-cycle function of TRBP
Yoosik Kim1, Jinah Yeo1, Jung Hyun Lee1
1Center for RNA Research, Institute for Basic Science, Seoul 151-742, South Korea; School of Biological Sciences, Seoul National University, Seoul 151-742, South Korea.
Abstract:
TRBP functions as both a Dicer cofactor and a PKR inhibitor. However, the role of TRBP in microRNA (miRNA) biogenesis is controversial and its regulation of PKR in mitosis remains unexplored. Here, we generate TRBP knockout cells and find altered Dicer-processing sites in a subset of miRNAs but no effect on Dicer stability, miRNA abundance, or Argonaute loading. By generating PACT, another Dicer interactor, and TRBP/PACT double knockout (KO) cells, we further show that TRBP and PACT do not functionally compensate for one another and that only TRBP contributes to Dicer processing. We also report that TRBP is hyperphosphorylated by JNK in M phase when PKR is activated by cellular double-stranded RNAs (dsRNAs). Hyperphosphorylation potentiates the inhibitory activity of TRBP on PKR, suppressing PKR in M-G1 transition. By generating human TRBP KO cells, our study clarifies the role of TRBP and unveils negative feedback regulation of PKR through TRBP phosphorylation.
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