Alu elements belong to the primate-specific SINE family of retrotransposons and constitute almost 11% of the human genome. Alus 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.

Alu元素属于灵长类特异性SINE逆转录转座子家族，几乎占人类基因组的11％。Alu通过RNA聚合酶（Pol）III转录，并在自主LINE逆转录元件的帮助下重新插入基因组。由于Alu元素优先位于富含基因的区域附近或内部，因此它们可以通过DNA和RNA水平上不同的作用机制来影响基因表达。在这篇综述中，我们集中于Alu元素如何普遍参与基因调控的最新进展。我们讨论了与基因，Pol-III转录的游离Alu紧密相关的Alu DNA序列的影响嵌入在编码或非编码RNA转录物中的RNA和Pol-II转录的Alu RNA。最近对Alu功能的阐明揭示了这些低估的自私或垃圾DNA序列在人类基因组中的作用。