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Analysis of Termination of Transcription Using BrUTP-strand-specific Transcription Run-on TRO Approach
Published on: March 12, 2017
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Microprocessor mediates transcriptional termination of long noncoding RNA transcripts hosting microRNAs
Ashish Dhir1, Somdutta Dhir1, Nick J Proudfoot1
1Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.
Nature Structural & Molecular Biology
|March 3, 2015
Summary
Most long noncoding RNAs containing microRNAs (miRNAs) are terminated by Microprocessor cleavage, not polyadenylation. This RNase III-mediated process prevents transcriptional readthrough and interference with other genes.
Area of Science:
- Molecular Biology
- Gene Regulation
- RNA Processing
Background:
- MicroRNAs (miRNAs) are key regulators of gene expression at the post-transcriptional level.
- Mammalian miRNA biogenesis involves the Microprocessor complex for cotranscriptional cleavage of RNA polymerase II (Pol II) transcripts.
- While many miRNAs are intronic, a significant portion originates from long noncoding RNAs (lncRNAs), with poorly understood processing mechanisms.
Purpose of the Study:
- To investigate the transcript processing and termination mechanisms of lncRNAs containing miRNAs (lnc-pri-miRNAs).
- To determine if lnc-pri-miRNAs utilize the canonical cleavage-and-polyadenylation pathway for termination.
- To elucidate the role of the Microprocessor complex in lnc-pri-miRNA processing and its impact on gene expression.
Main Methods:
- Detailed characterization of the liver-specific lnc-pri-miR-122 transcript.
- Genome-wide analysis of lnc-pri-miRNA processing in human cell lines.
- Assessment of Microprocessor complex activity and its effect on transcription termination.
Main Results:
- Most lnc-pri-miRNAs are not terminated by the canonical cleavage-and-polyadenylation pathway.
- Microprocessor cleavage serves as the primary termination mechanism for lnc-pri-miRNAs.
- Inactivation of the Microprocessor complex results in extensive transcriptional readthrough of lnc-pri-miRNAs.
- Transcriptional readthrough interferes with the expression of downstream genes.
Conclusions:
- A novel RNase III-mediated, polyadenylation-independent mechanism for Pol II transcription termination in mammalian cells is defined.
- Microprocessor-dependent termination is crucial for preventing transcriptional interference from lnc-pri-miRNAs.
- This finding reveals a new layer of gene regulation involving lncRNA processing and transcription termination.
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