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Updated: May 8, 2026

A Reporter Assay to Analyze Intronic microRNA Maturation in Mammalian Cells
06:48

A Reporter Assay to Analyze Intronic microRNA Maturation in Mammalian Cells

Published on: June 16, 2022

Dynamic localisation of mature microRNAs in Human nucleoli is influenced by exogenous genetic materials

Zhou Fang Li1, Yi Min Liang, Pui Ngan Lau

  • 1Departments of Biology and Chemistry, City University of Hong Kong, Hong Kong, China.

Plos One
|August 14, 2013
PubMed

Insights

MicroRNAs (miRNAs) accumulate in the nucleolus, not just the cytoplasm. Their nucleolar presence shifts to the cytoplasm upon detecting foreign DNA or RNA, suggesting a role in cellular defense.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Genetics

Background:

  • MicroRNAs (miRNAs) are primarily known for their cytoplasmic function in gene silencing via RNA-induced silencing complexes.
  • Emerging evidence suggests miRNAs are also present in other cellular compartments, including the nucleus and nucleolus.

Purpose of the Study:

  • To systematically identify and localize miRNAs within the nucleoli of mammalian cells.
  • To investigate the dynamic regulation of nucleolar miRNA localization in response to cellular stimuli.

Main Methods:

  • Systematic screening of HeLa cell nucleoli for abundant miRNAs.
  • In situ hybridization to localize specific miRNAs (e.g., miR-191, miR-484) in nucleoli across various cell lines.
  • Exposure of cells to exogenous nucleic acids (DNA, RNA) and viral infection to observe miRNA redistribution.
  • Treatment with Leptomycin B to assess the role of Exportin-1.

Main Results:

  • Identified 11 abundant miRNAs with significant nucleolar accumulation.
  • Confirmed nucleolar localization of specific miRNAs in diverse human and rodent cell lines.
  • Demonstrated that nucleolar miRNA association is stable under stress but rapidly disrupted by exogenous nucleic acids and viral infection, leading to cytoplasmic redistribution.
  • Showed that Leptomycin B affects miRNA partitioning, implicating Exportin-1 in nucleocytoplasmic shuttling.

Conclusions:

  • Reveals a novel aspect of miRNA biology with significant nucleolar localization.
  • Suggests a potential role for nucleolar miRNAs in the cellular response to foreign genetic material.
  • Highlights the dynamic subcellular trafficking of miRNAs, potentially mediated by Exportin-1.

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