Regulation of eukaryotic gene expression by the untranslated gene regions and other non-coding elements

Abstract

There is now compelling evidence that the complexity of higher organisms correlates with the relative amount of non-coding RNA rather than the number of protein-coding genes. Previously dismissed as "junk DNA", it is the non-coding regions of the genome that are responsible for regulation, facilitating complex temporal and spatial gene expression through the combinatorial effect of numerous mechanisms and interactions working together to fine-tune gene expression. The major regions involved in regulation of a particular gene are the 5' and 3' untranslated regions and introns. In addition, pervasive transcription of complex genomes produces a variety of non-coding transcripts that interact with these regions and contribute to regulation. This review discusses recent insights into the regulatory roles of the untranslated gene regions and non-coding RNAs in the control of complex gene expression, as well as the implications of this in terms of organism complexity and evolution.

Fig. 1

Regulatory elements within the noncoding gene regions. The centre image shows a typical gene, with exons indicated in grey. The orange rectangles indicate intronic enhancer elements. a Promoter region regulatory elements (adapted from [162]). Upstream and downstream promoter elements situated outside of the core promoter region are indicated by the arrows. b Regulatory elements in the 5′UTR. c Regulatory elements in the 3′UTR