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A Reporter Assay to Analyze Intronic microRNA Maturation in Mammalian Cells
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Stress-induced reversal of microRNA repression and mRNA P-body localization in human cells

S N Bhattacharyya1, R Habermacher, U Martine

  • 1Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.

Cold Spring Harbor Symposia on Quantitative Biology
|March 27, 2007
PubMed

Insights

MicroRNA (miRNA) repression of gene expression can be reversed. Stress conditions can release specific mRNAs from miRNA-induced inhibition, revealing a dynamic regulatory mechanism.

Area of Science:

  • Molecular Biology
  • Gene Regulation

Background:

  • MicroRNAs (miRNAs) regulate gene expression post-transcriptionally by binding to mRNA 3'UTRs.
  • miRNA-mediated repression can involve translational inhibition or mRNA degradation.
  • The reversibility of miRNA-mediated repression is largely unexplored.

Purpose of the Study:

  • To investigate whether miRNA-mediated repression of gene expression is a reversible process.
  • To identify conditions and mechanisms that can relieve miRNA-induced inhibition of specific mRNAs.

Main Methods:

  • Utilized reporter assays with CAT-1 mRNA 3'UTR fragments in human hepatoma cells.
  • Exposed cells to various stress conditions to observe changes in gene expression.
  • Analyzed mRNA localization (P bodies vs. polysomes) and protein binding (HuR).

Main Results:

  • Stress conditions reversed miR-122-induced repression of CAT-1 mRNA and reporter constructs.
  • Derepressed CAT-1 mRNA was released from P bodies and recruited to polysomes.
  • Reversal of repression required HuR binding to the CAT-1 3'UTR.

Conclusions:

  • P bodies function as storage sites for miRNA-inhibited mRNAs.
  • miRNA-mediated repression is a reversible process influenced by cellular stress.
  • Proteins binding to the 3'UTR, like HuR, can modulate miRNA repression efficacy.

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