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Poly(A)-binding protein modulates mRNA susceptibility to cap-dependent miRNA-mediated repression
Robert W Walters1, Shelton S Bradrick, Matthias Gromeier
1Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 27710, USA.
RNA (New York, N.Y.)
|November 26, 2009
Summary
MicroRNAs (miRNAs) require the 5' cap and 3' poly(A) tail for maximum gene silencing. Poly(A)-binding protein (PABP) antagonizes miRNA function by inhibiting mRNA deadenylation, thus affecting miRNA efficacy.
Area of Science:
- Molecular Biology
- Gene Regulation
Background:
- MicroRNAs (miRNAs) are key regulators of gene expression, mediating post-transcriptional silencing.
- While miRNA repressive effects are known, the exact mechanisms of gene modulation remain unclear.
Purpose of the Study:
- To investigate the role of mRNA cis-acting elements (5' cap, 3' poly(A) tail) in miRNA-mediated gene silencing.
- To elucidate the function of poly(A)-binding protein (PABP) in miRNA activity.
Main Methods:
- Utilized human cell culture to examine miRNA effects on target transcripts with natural and artificial 3' UTRs.
- Manipulated PABP levels and activity to assess its impact on miRNA silencing.
- Evaluated the influence of mRNA 5' UTR structures on miRNA susceptibility.
Main Results:
- Confirmed that the 5' m(7)G cap and 3' poly(A) tail are crucial for robust miRNA repression.
- Demonstrated that cap-independent translation initiation structures do not abolish miRNA susceptibility when essential cis-acting elements are present.
- Observed an inverse correlation between PABP levels/activity and miRNA silencing strength, partly via PABP's antagonism of target mRNA deadenylation.
Conclusions:
- The 5' cap and 3' poly(A) tail are essential for efficient miRNA-mediated gene silencing.
- PABP plays a significant role in modulating miRNA efficacy by counteracting mRNA deadenylation.
- These findings provide a deeper understanding of the factors governing miRNA activity.
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