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Published on: May 1, 2021
Evidence for a cytoplasmic microprocessor of pri-miRNAs
Jillian S Shapiro1, Ryan A Langlois, Alissa M Pham
1Department of Microbiology, Mount Sinai School of Medicine, New York, New York 10029, USA.
RNA (New York, N.Y.)
|May 29, 2012
Summary
Virus infection triggers Drosha enzyme relocation to the cytoplasm, enabling the processing of viral microRNAs (miRNAs) without affecting host miRNAs. This reveals a novel cytoplasmic function for Drosha in viral RNA processing.
Area of Science:
- Molecular Biology
- Virology
- RNA Biology
Background:
- MicroRNAs (miRNAs) are key regulators of gene expression via post-transcriptional silencing.
- Canonical miRNA biogenesis initiates in the nucleus with the microprocessor complex.
- Noncanonical miRNA biogenesis pathways, including cytoplasmic processing, are less understood.
Purpose of the Study:
- To characterize the molecular mechanisms and components involved in processing virus-derived cytoplasmic primary miRNAs (c-pri-miRNAs).
- To investigate the role of Drosha, a nuclear RNase III enzyme, in cytoplasmic miRNA processing during viral infection.
Main Methods:
- RNA in situ hybridization to visualize RNA localization.
- Inhibition of cellular division to assess nuclear involvement.
- Genetic studies to determine enzyme dependencies.
- Deep sequencing to analyze miRNA profiles.
Main Results:
- Virus infection induced Drosha relocalization from the nucleus to the cytoplasm.
- c-pri-miRNA processing occurred independently of nuclear involvement but required Drosha.
- Cytoplasmic Drosha facilitated robust viral miRNA synthesis without altering endogenous miRNA levels.
Conclusions:
- Drosha exhibits a novel cytoplasmic function in processing viral-derived, highly structured RNAs during infection.
- This noncanonical pathway allows for efficient viral miRNA production in the cytoplasm.
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