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Updated: Mar 30, 2026
11:52
Analysis of LINE-1 Retrotransposition at the Single Nucleus Level
Published on: April 23, 2016
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A 3' Poly(A) Tract Is Required for LINE-1 Retrotransposition
Aurélien J Doucet1, Jeremy E Wilusz2, Tomoichiro Miyoshi1
1Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48109-5618, USA.
Molecular Cell
|November 21, 2015
Summary
The 3' poly(A) tail is crucial for L1 retrotransposons to mobilize RNA. Adding a poly(A) tract restores retrotransposition, highlighting its importance for mobilizing vast human DNA sequences.
Area of Science:
- Molecular Biology
- Genetics
- Genomics
Background:
- L1 retrotransposons mobilize their own RNA (cis) and other RNAs (trans).
- All mobilized RNAs share a 3' polyadenosine (poly(A)) tract.
- MALAT1, a non-polyadenylated long non-coding RNA, forms a triple helix at its 3' end.
Purpose of the Study:
- To investigate the role of the 3' poly(A) tract in L1 retrotransposition.
- To determine if alternative 3' structures can replace the poly(A) tract's function.
- To understand the critical elements for both cis and trans mobilization by L1 retrotransposons.
Main Methods:
- Replaced L1 polyadenylation signal with MALAT1-derived sequences (L1/MALAT RNAs).
- Assessed RNA accumulation, translation, and retrotransposition efficiency in cells.
- Introduced poly(A) tracts of varying lengths downstream of the MALAT1 sequence.
Main Results:
- L1/MALAT RNAs accumulated, were translated, but failed to retrotranspose in cis.
- Restoring a 3' poly(A) tract (16 or 40 bases) re-enabled cis retrotransposition.
- The poly(A) tract was also essential for ORF2p-mediated trans mobilization of RNAs.
Conclusions:
- A 3' poly(A) tract is indispensable for L1 retrotransposition, both in cis and trans.
- Alternative 3' RNA structures, like the MALAT1 triple helix, cannot substitute for the poly(A) tract.
- This finding is significant given that poly(A) tracts are critical for mobilizing approximately one billion base pairs of human DNA.
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