ALUternative Regulation for Gene Expression. Issue 7 (July 2017)

• Record Type: Journal Article
• Authors: Chen, Ling-Ling; Yang, Li
• Is Part Of: Trends in cell biology. Volume 27:Issue 7(2017)
• Page Start: 480
• Page End: 490
• Publication Date: 2017-07
• Subjects: Cytology -- Periodicals; Cytology -- Research -- Periodicals; 571.6
• DOI: 10.1016/j.tcb.2017.01.002
• Languages: English
• ISSNs: 0962-8924

Abstract

Abstract : Alu elements belong to the primate-specific SINE family of retrotransposons and constitute almost 11% of the human genome. Alu s are transcribed by RNA polymerase (Pol) III and are inserted back into the genome with the help of autonomous LINE retroelements. Since Alu elements are preferentially located near to or within gene-rich regions, they can affect gene expression by distinct mechanisms of action at both DNA and RNA levels. In this review we focus on recent advances of how Alu elements are pervasively involved in gene regulation. We discuss the impacts of Alu DNA sequences that are in close proximity to genes, Pol-III-transcribed free Alu RNAs, and Pol-II-transcribed Alu RNAs that are embedded within coding or noncoding RNA transcripts. The recent elucidation of Alu functions reveals previously underestimated roles of these selfish or junk DNA sequences in the human genome. Trends: Primate-specific Alu s constitute 11% of the human genome, with >1 million copies, and their genomic distribution is biased toward gene-rich regions. The functions of Alu s are highly associated with their sequence and structural features. Alu s can regulate gene expression by serving as cis elements. Pol-III-transcribed free Alu s mainly affect Pol II transcription and mRNA translation in trans . Embedded Alu s within Pol-II-transcribed mRNAs can impact their host gene expression through the regulation of alternative splicing, and RNA stability and translation. Nearly half of annotated Alu s are located in introns; RNA pairing formed by orientation-opposite Alu s across introns promotes circRNA biogenesis.