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Scientifica
Volume 2012, Article ID 545328, 11 pages
http://dx.doi.org/10.6064/2012/545328
Review Article

Alu Mobile Elements: From Junk DNA to Genomic Gems

Nutrition Research Institute, The University of North Carolina at Chapel Hill, 500 Laureate Way, Kannapolis, NC 28081, USA

Received 21 October 2012; Accepted 6 November 2012

Academic Editors: Y. Ge, A. H. Salem, and H. Schatten

Copyright © 2012 Sami Dridi. 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.

Abstract

Alus, the short interspersed repeated sequences (SINEs), are retrotransposons that litter the human genomes and have long been considered junk DNA. However, recent findings that these mobile elements are transcribed, both as distinct RNA polymerase III transcripts and as a part of RNA polymerase II transcripts, suggest biological functions and refute the notion that Alus are biologically unimportant. Indeed, Alu RNAs have been shown to control mRNA processing at several levels, to have complex regulatory functions such as transcriptional repression and modulating alternative splicing and to cause a host of human genetic diseases. Alu RNAs embedded in Pol II transcripts can promote evolution and proteome diversity, which further indicates that these mobile retroelements are in fact genomic gems rather than genomic junks.