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CUG-binding protein represses translation of p27Kip1 mRNA through its internal ribosomal entry site

Yuhuan Zheng1, W Keith Miskimins

  • 1Cancer Biology Research Center, Sanford Research/USD, Sioux Falls, and Division of Basic Biomedical Sciences, Sanford School of Medicine of the University of South Dakota, Vermillion, SD, USA. yuzheng@mdanderson.org

RNA Biology
|April 22, 2011
PubMed

Insights

The RNA-binding protein CUGBP1 binds to p27 mRNA

Area of Science:

  • Molecular Biology
  • Cell Cycle Regulation
  • RNA-binding proteins

Background:

  • The cyclin-dependent kinase inhibitor p27 (Kip1) is crucial for eukaryotic cell cycle control.
  • The p27 mRNA's 5'-untranslated region contains an internal ribosome entry site (IRES) potentially regulating p27 synthesis.
  • RNA-binding proteins can modulate mRNA translation and cellular processes.

Purpose of the Study:

  • To investigate the interaction between CUGBP1 and the p27 mRNA 5'-untranslated region.
  • To determine the effect of CUGBP1 on p27 expression and IRES-mediated translation.
  • To elucidate the role of CUGBP1 in regulating p27 protein levels.

Main Methods:

  • RNA immunoprecipitation assays to detect CUGBP1-p27 mRNA interaction.
  • Western blotting to assess p27 protein levels.
  • Reporter assays to measure p27 IRES activity.
  • siRNA-mediated knockdown and overexpression of CUGBP1.
  • In vitro translation assays with recombinant CUGBP1.

Main Results:

  • CUGBP1 directly interacts with the 5'-untranslated region of human p27 mRNA.
  • Overexpression of CUGBP1 inhibits endogenous p27 expression and p27 IRES activity.
  • Knockdown of CUGBP1 using siRNA enhances p27 protein levels and stimulates p27 IRES activity.
  • Recombinant CUGBP1 represses p27 IRES-driven translation in vitro.
  • The cytosolic form of CUGBP1 exhibits efficient binding to the p27 5'-untranslated region.

Conclusions:

  • CUGBP1 acts as a negative regulator of p27 expression.
  • CUGBP1 inhibits translation initiation via the p27 IRES.
  • CUGBP1's interaction with p27 mRNA contributes to the regulation of cell cycle progression.

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