Emerging fundamental roles for non-coding RNA species in toxicology.

microRNAs (miRNAs) are a large family of small regulatory RNA molecules found in all multicellular organisms. Since their discovery in 2001, there has been impressive progress in miRNA research, and a great deal is now known about the biosynthesis of miRNAs and their regulatory role in translation. It is becoming increasingly clear that miRNAs have fundamental roles to play in cellular responses to xenobiotic stress, the development of pathophysiological changes and other toxicological phenomenon such as susceptibility and resistance. Furthermore, the expression of miRNAs, like many of the genes important in toxicology, can be regulated by xenobiotics and DNA methylation. In this article we review the present understanding of the miRNA field with particular reference to toxicology. We also give an insight into our current projects within this exciting area and highlight some of the new challenges that now face miRNA research.