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Journal of Biomedicine and Biotechnology
Volume 2006, Article ID 32713, 8 pages
Review Article

The Potential Regulation of L1 Mobility by RNA Interference

1Department of Pathology and Laboratory Medicine, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6055, USA
2Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, Basel 4058, Switzerland

Received 6 August 2005; Revised 12 December 2005; Accepted 20 December 2005

Copyright © 2006 Shane R. Horman et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The hypothesis that RNA interference constrains L1 mobility seems inherently reasonable: L1 mobility can be dangerous and L1 RNA, the presumed target of RNAi, serves as a critical retrotransposition intermediate. Despite its plausibility, proof for this hypothesis has been difficult to obtain. Studies attempting to link the L1 retrotransposition frequency to alterations in RNAi activity have been hampered by the long times required to measure retrotransposition frequency, the pleiotropic and toxic effects of altering RNAi over similar time periods, and the possibility that other cellular machinery may contribute to the regulation of L1s. Another problem is that the commonly used L1 reporter cassette may serve as a substrate for RNAi. Here we review the L1-RNAi hypothesis and describe a genetic assay with a modified reporter cassette that detects approximately 4 times more L1 insertions than the conventional retrotransposition assay.