RNA Stability: Chemistry, Measurement and Modulation

Molecules composed of RNA perform many roles that are vital for the life and reproduction of all cellular organisms and viruses, one of which is the role of messengers that carry from genes the information required for the production of protein. A typical feature of messenger RNA (mRNA) is its relative instability, which ensures that the production of any particular protein soon comes to an end when it is no longer required and synthesis of the message is downregulated. Moreover, while a transcript is being produced, its rate of decay is as important as its rate of synthesis in determining its cellular concentration and thus, to a large extent, its level of function. The turnover of mRNA, and indeed all other types of RNA, is mediated by multiple ribonucleases. The activity of these enzymes in cells can be inhibited rapidly by chemical treatments; thus, for many experimental systems their presence does not pose a significant barrier to the study of gene regulation at the RNA level. However, the development of RNA-based therapeutics such as small interfering RNAs and aptamers has required the introduction of modifications to prevent their degradation by ribonucleases within the cells and body fluids of humans. This article describes the properties of RNA that make it susceptible to ribonucleases and the techniques used to determine the stability of RNA molecules. It also provides examples of how RNA stability in livings cells is being modulated for biotechnology and clinical applications, and it reviews the strategies that are being adopted to increase the in vivo stability of RNAs with therapeutic potential.