Dissection of affinity captured LINE-1 macromolecular complexes
- Massachusetts General Hospital, United States
- Moscow Institute of Physics and Technology, Russian Federation
- The Rockefeller University, United States
- NYU Langone Medical Center, United States
- Johns Hopkins University School of Medicine, United States
- Novosibirsk State University, Russian Federation
Abstract
Long Interspersed Nuclear Element-1 (LINE-1, L1) is a mobile genetic element active in human genomes. L1-encoded ORF1 and ORF2 proteins bind L1 RNAs, forming ribonucleoproteins (RNPs). These RNPs interact with diverse host proteins, some repressive and others required for the L1 lifecycle. Using differential affinity purifications, quantitative mass spectrometry, and next generation RNA sequencing, we have characterized the proteins and nucleic acids associated with distinctive, enzymatically active L1 macromolecular complexes. Among them, we describe a cytoplasmic intermediate that we hypothesize to be the canonical ORF1p/ORF2p/L1-RNA-containing RNP, and we describe a nuclear population containing ORF2p, but lacking ORF1p, which likely contains host factors participating in target-primed reverse transcription.
Data availability
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RNA-seq FASTAQ filesPublicly available at ProteomeXchange (accession no: PXD008542).
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RNAs associated with affinity captured LINE-1 ribonucleoproteinsPublicly available at the NCBI Gene Expression Omnibus (accession no: GSE108270).
Article and author information
Author details
Funding
National Institutes of Health (P41GM109824)
- Michael P Rout
National Institutes of Health (P41GM103314)
- Brian T Chait
National Institutes of Health (P50GM107632)
- Jef D Boeke
National Institutes of Health (R01GM654321)
- Jef D Boeke
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2018, Taylor et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Dissection of affinity captured LINE-1 macromolecular complexes
eLife 7:e30094.
https://doi.org/10.7554/eLife.30094
Further reading
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- Cell Biology
- Genetics and Genomics
The mechanisms by which a retrotransposon called LINE-1 duplicates itself and spreads through the human genome are becoming clearer.
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Stem cell differentiation involves a global increase in protein synthesis to meet the demands of specialized cell types. However, the molecular mechanisms underlying this translational burst and the involvement of initiation factors remains largely unknown. Here, we investigate the role of eukaryotic initiation factor 3 (eIF3) in early differentiation of human pluripotent stem cell (hPSC)-derived neural progenitor cells (NPCs). Using Quick-irCLIP and alternative polyadenylation (APA) Seq, we show eIF3 crosslinks predominantly with 3’ untranslated region (3’-UTR) termini of multiple mRNA isoforms, adjacent to the poly(A) tail. Furthermore, we find that eIF3 engagement at 3’-UTR ends is dependent on polyadenylation. High eIF3 crosslinking at 3’-UTR termini of mRNAs correlates with high translational activity, as determined by ribosome profiling, but not with translational efficiency. The results presented here show that eIF3 engages with 3’-UTR termini of highly translated mRNAs, likely reflecting a general rather than specific regulatory function of eIF3, and supporting a role of mRNA circularization in the mechanisms governing mRNA translation.
