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An E2F/miR-20a autoregulatory feedback loop

Yannick Sylvestre1, Vincent De Guire, Emmanuelle Querido

  • 1Département de Biochimie, Université de Montréal, Montréal, Quebec H3C 3J7, Canada.

The Journal of Biological Chemistry
|December 1, 2006
PubMed

Insights

MicroRNAs (miRNAs) regulate E2F transcription factors, crucial for cell cycle control. This study reveals miR-20a

Area of Science:

  • Molecular Biology
  • Genetics
  • Cancer Research

Background:

  • E2F transcription factors (E2F1-3) are key regulators of cell cycle progression and apoptosis.
  • E2F activity is controlled by retinoblastoma proteins, but also by transcriptional, post-translational, and stability mechanisms.
  • MicroRNAs (miRNAs) from the miR-17-92 cluster regulate E2F1 translation.

Purpose of the Study:

  • To investigate the role of miR-20a, a member of the miR-17-92 cluster, in regulating E2F2 and E2F3 expression.
  • To explore the autoregulatory feedback loop between E2F factors and the miR-17-92 cluster.
  • To determine the anti-apoptotic function of miR-20a.

Main Methods:

  • Luciferase reporter assays to assess miRNA-mediated translation inhibition.
  • Western blotting to detect protein levels.
  • Chromatin immunoprecipitation to identify promoter binding.
  • Cell viability assays and apoptosis measurements after miRNA manipulation.

Main Results:

  • miR-20a directly modulates the translation of E2F2 and E2F3 mRNAs through binding sites in their 3'-untranslated regions.
  • Endogenous E2F1, E2F2, and E2F3 activate the transcription of the miR-17-92 cluster, indicating a feedback loop.
  • Overexpression of miR-20a reduced apoptosis in prostate cancer cells, while inhibition increased cell death.

Conclusions:

  • An autoregulatory feedback loop exists between E2F1-3 and miR-20a, crucial for preventing abnormal E2F accumulation.
  • miR-20a exhibits anti-apoptotic properties, potentially contributing to the oncogenic role of the miR-17-92 cluster.
  • This regulatory axis plays a significant role in controlling cellular proliferation and apoptosis.

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