LINE-1 ORF1 protein enhances Alu SINE retrotransposition

Retroelements have contributed over one third of the human genome mass. The currently active LINE-1 (L1) codes for two proteins (ORF1p and ORF2p), both strictly required for retrotransposition. In contrast, the non-coding parasitic SINE (Alu) only appears to need the L1 ORF2p for its own amplificati...

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Bibliographic Details
Published in:Gene 2008-08, Vol.419 (1), p.1-6
Main Authors: Wallace, Nicholas, Wagstaff, Bradley J., Deininger, Prescott L., Roy-Engel, Astrid M.
Format: Article
Language:English
Subjects:
Alu
Alu Elements
Animals
Cells, Cultured
Chickens
Endonucleases - genetics
Endonucleases - metabolism
HeLa Cells
Humans
L1 ORF1 protein
LINE-1
Long Interspersed Nucleotide Elements
Mice
Proteins - genetics
Proteins - metabolism
Retroelement
Retrotransposition
RNA-Directed DNA Polymerase - genetics
RNA-Directed DNA Polymerase - metabolism
Sequence Deletion
Sequence Tagged Sites
SINE amplification
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Summary:Retroelements have contributed over one third of the human genome mass. The currently active LINE-1 (L1) codes for two proteins (ORF1p and ORF2p), both strictly required for retrotransposition. In contrast, the non-coding parasitic SINE (Alu) only appears to need the L1 ORF2p for its own amplification. This requirement was previously determined using a tissue culture assay system in human cells (HeLa). Because HeLa are likely to express functional L1 proteins, it is possible that low levels of endogenous ORF1p are necessary for the observed tagged Alu mobilization. By individually expressing ORF1 and ORF2 proteins from both human (L1 RP and LRE3) and rodent (L1 A102 and L1 spa) L1 sources, we demonstrate that increasing amounts of ORF1 expressing vector enhances tagged Alu mobilization in HeLa cells. In addition, using chicken fibroblast cells as an alternate cell culture source, we confirmed that ORF1p is not strictly required for Alu mobilization in our assay. Supporting our observations in HeLa cells, we find that tagged Alu retrotransposition is improved by supplementation of ORF1p in the cultured chicken cells. We postulate that L1 ORF1p plays either a direct or indirect role in enhancing the interaction between the Alu RNA and the required factors needed for its retrotransposition.
ISSN:0378-1119
1879-0038
DOI:10.1016/j.gene.2008.04.007